Creamy mushroom and spinach pasta bake is the kind of weeknight dinner that makes everyone at the table think you spent way more time on it than you actually did. One baking dish, simple ingredients, bubbling golden cheese on top — it is comfort food at its most satisfying and it comes together in about 45 minutes start to finish.
I make some version of this every few weeks from October through March, and honestly into spring too because my family requests it constantly. It hits that specific combination of creamy, cheesy and hearty without being heavy in a way that leaves you feeling sluggish. The mushrooms add a savory, almost meaty depth that makes this completely satisfying as a vegetarian main, and the spinach wilts into the sauce in a way that even vegetable skeptics tend to overlook entirely.
This one goes into regular rotation. I promise.
Why This Recipe Works
Table of Contents
The secret to a pasta bake that doesn’t dry out in the oven is a sauce that’s slightly looser than you think it needs to be before it goes in. Pasta absorbs liquid as it bakes and a sauce that seems perfectly coated in the pan will be tight and sticky by the time it comes out of the oven. Making the béchamel slightly thinner than a standard cream sauce compensates for this perfectly and the result is creamy and saucy all the way through rather than dry in the middle.
The second thing that makes this work is not overcooking the pasta before it goes into the bake. Cook it two minutes less than the package directions for al dente — it will finish cooking in the oven and if it goes in fully cooked it will be mushy by the time the cheese is golden.
What You’ll Need
For the pasta and vegetables:
- 12 ounces penne pasta
- 2 tablespoons olive oil
- 1 pound cremini or baby bella mushrooms, sliced
- 3 cloves garlic, minced
- 4 ounces fresh baby spinach
- 1 teaspoon fresh thyme leaves (or half teaspoon dried)
- Salt and black pepper to taste
For the béchamel sauce:
- 3 tablespoons unsalted butter
- 3 tablespoons all-purpose flour
- 2 cups whole milk, warmed
- 1 cup vegetable or chicken broth
- Half teaspoon garlic powder
- Half teaspoon onion powder
- Quarter teaspoon nutmeg
- Salt and white pepper to taste
For the topping:
- 2 cups shredded mozzarella cheese, divided
- Half cup freshly grated Parmesan cheese
- Half cup Gruyère, shredded (optional but highly recommended)
How to Make Creamy Mushroom and Spinach Pasta Bake
Step 1: Preheat and Prep
Preheat your oven to 375 degrees F. Lightly grease a 9×13 inch baking dish with butter or cooking spray and set aside. Bring a large pot of heavily salted water to a boil.
Step 2: Cook the Pasta
Cook the penne in boiling salted water for two minutes less than the package directions for al dente. It should still have a slight firmness at the center — it will finish cooking in the oven. Drain and set aside. Do not rinse.
Step 3: Sauté the Mushrooms
While the pasta cooks, heat olive oil in a large skillet over medium-high heat. Add the sliced mushrooms in a single layer — if your pan isn’t large enough, do this in two batches. Do not stir for the first two to three minutes. This is the most important step: letting the mushrooms sit undisturbed allows them to release their moisture and then caramelize rather than steam. Steamed mushrooms are soft and pale. Caramelized mushrooms are golden, deeply savory and genuinely delicious.
Once the mushrooms are golden on one side, stir and continue cooking for another three to four minutes until most of the liquid has evaporated and the edges are nicely browned. Add the garlic and thyme and cook for one more minute until fragrant. Add the spinach and toss until just wilted, about one to two minutes. Season generously with salt and pepper. Remove from heat and set aside.
Step 4: Make the Béchamel
In a medium saucepan over medium heat, melt the butter. Add the flour and whisk constantly for one to two minutes — this cooks out the raw flour taste and is the step most people skip too quickly. The mixture should look like a pale paste and smell slightly nutty.
Slowly pour in the warmed milk about a quarter cup at a time, whisking constantly after each addition until fully incorporated before adding more. Once all the milk is in, add the broth and continue whisking until the sauce is smooth and beginning to thicken, about five to seven minutes. It should coat the back of a spoon but still pour easily — remember, slightly looser than you think.
Remove from heat and stir in the garlic powder, onion powder, nutmeg and a generous amount of salt and white pepper. Taste and adjust — this sauce needs to be well seasoned because it’s carrying the whole dish. Stir in one cup of the shredded mozzarella and the Parmesan until melted and smooth.
Step 5: Combine
In a large bowl or directly in the pot you cooked the pasta in, combine the drained pasta, the mushroom and spinach mixture and the béchamel sauce. Toss until everything is evenly coated. Pour into the prepared baking dish and spread into an even layer.
Step 6: Top and Bake
Sprinkle the remaining cup of mozzarella and the Gruyère evenly over the top. The cheese layer should be generous — this is not the place for restraint.
Bake uncovered at 375 degrees F for 20 to 25 minutes until the cheese is completely melted, bubbling and golden in spots. For deeper browning on top, switch to the broiler for the last two to three minutes and watch it carefully.
Step 7: Rest and Serve
Let the pasta bake rest for five minutes before serving. This allows the sauce to settle slightly and makes it easier to serve in clean portions. Serve directly from the baking dish.
Variations Worth Trying
Add protein: Rotisserie chicken shredded and stirred in with the mushrooms and spinach makes this a heartier main. Italian sausage, browned and crumbled, is excellent. Crispy pancetta or bacon adds a salty, smoky note that plays beautifully against the creamy sauce.
Make it gluten-free: Use your favorite gluten-free penne and substitute the all-purpose flour in the béchamel with a one-to-one gluten-free flour blend or cornstarch. The sauce works exactly the same way.
Switch up the mushrooms: Cremini are the everyday choice, but a mix of cremini and shiitake adds more complex, earthy flavor. Oyster mushrooms are beautiful and delicate. Wild mushrooms when in season make this feel genuinely special.
Add sun-dried tomatoes: A quarter cup of chopped oil-packed sun-dried tomatoes stirred into the mixture before baking adds concentrated tomato flavor and a gorgeous color contrast.
Make it ahead: Assemble the entire dish, cover tightly with foil and refrigerate for up to 24 hours before baking. Add five to ten minutes to the bake time if going directly from the refrigerator to the oven.
What to Serve With It
This pasta bake is a complete meal on its own, but a simple green salad with a bright vinaigrette cuts through the richness beautifully. Crusty garlic bread for scooping up the extra sauce is non-negotiable in my house. A glass of white wine — a lightly oaked Chardonnay or a Pinot Grigio — pairs perfectly with the creamy mushroom and Gruyère flavors.
Make Ahead and Storage
Make ahead: Assemble the dish up to 24 hours in advance, cover and refrigerate unbaked. Bring to room temperature for 20 minutes before baking.
Refrigerator: Leftovers keep covered in the refrigerator for up to four days. The flavors actually develop overnight and this is one of those dishes that’s genuinely delicious the next day.
Reheating: Reheat individual portions in the microwave with a splash of milk stirred in to loosen the sauce. Reheat the full dish covered with foil at 350 degrees F for 20 minutes until heated through.
Freezer: This pasta bake freezes well unbaked — assemble in a freezer-safe dish, wrap tightly and freeze for up to two months. Thaw overnight in the refrigerator before baking.
Frequently Asked Questions
Can I use a different pasta shape? Yes — rigatoni, ziti and rotini all work beautifully. Avoid long pasta shapes like spaghetti or linguine, which don’t hold up as well in a baked pasta dish. The ridged or tubular shapes hold sauce better and give the dish more structure.
Can I use frozen spinach instead of fresh? Yes, but thaw it completely and squeeze out as much moisture as possible before adding it to the mushrooms. Frozen spinach holds significantly more water than fresh and if you don’t press it dry it will water down the sauce.
Why are my mushrooms releasing too much liquid? Two reasons: the pan isn’t hot enough or the mushrooms are overcrowded. Mushrooms need high heat and space to caramelize — if they’re packed too closely they steam in their own moisture rather than browning. Use a large pan and cook in batches if needed.
Can I make this without the béchamel and use cream instead? Heavy cream can be substituted for the béchamel for a slightly less structured but still delicious result. Use about 1.5 cups of heavy cream warmed with the garlic powder, onion powder and nutmeg, then proceed with the recipe. The béchamel gives a creamier, more cohesive sauce but the cream version is faster.
What cheese melts best on top? Mozzarella gives you the classic stretchy melt. Gruyère adds nutty, complex flavor. Fontina is an excellent alternative to Gruyère with a beautiful melt. Provolone is another great option. Avoid cheeses that don’t melt well like feta or cotija for the topping.
This creamy mushroom and spinach pasta bake is the definition of a recipe that earns permanent status in your dinner rotation — the kind of dish that feels special enough for company but easy enough for a Tuesday night when you need something comforting and you need it without a lot of drama. Make it once and you’ll understand why I make it every few weeks without question.
Recipe Card
Creamy Mushroom and Spinach Pasta Bake
Prep time: 20 minutes Cook time: 25 minutes Total time: 45 minutes Servings: 6 to 8 Category: Main dish, Pasta Cuisine: American, Italian-inspired
Ingredients
Pasta and vegetables:
- 12 ounces penne pasta
- 2 tablespoons olive oil
- 1 pound cremini mushrooms, sliced
- 3 cloves garlic, minced
- 4 ounces fresh baby spinach
- 1 teaspoon fresh thyme leaves
- Salt and black pepper to taste
Béchamel sauce:
- 3 tablespoons unsalted butter
- 3 tablespoons all-purpose flour
- 2 cups whole milk, warmed
- 1 cup vegetable or chicken broth
- Half teaspoon garlic powder
- Half teaspoon onion powder
- Quarter teaspoon nutmeg
- Salt and white pepper to taste
Topping:
- 2 cups shredded mozzarella, divided
- Half cup freshly grated Parmesan
- Half cup shredded Gruyère
Instructions
- Preheat oven to 375 degrees F. Grease a 9×13 inch baking dish.
- Cook penne two minutes less than package directions. Drain and set aside.
- Heat olive oil in a large skillet over medium-high heat. Cook mushrooms undisturbed for two to three minutes until golden, then stir and cook three to four minutes more until liquid has evaporated.
- Add garlic and thyme, cook one minute. Add spinach and toss until wilted. Season with salt and pepper. Remove from heat.
- Melt butter in a saucepan over medium heat. Add flour and whisk one to two minutes. Slowly whisk in warmed milk quarter cup at a time until smooth. Add broth and whisk until sauce thickens and coats a spoon, five to seven minutes.
- Remove sauce from heat. Season with garlic powder, onion powder, nutmeg, salt and white pepper. Stir in one cup mozzarella and the Parmesan until melted.
- Combine pasta, mushroom mixture and sauce. Pour into baking dish.
- Top with remaining mozzarella and Gruyère.
- Bake uncovered 20 to 25 minutes until bubbly and golden. Broil two to three minutes for deeper browning if desired.
- Rest five minutes before serving.
Notes
- Cook pasta two minutes less than package directions — it finishes in the oven
- Do not crowd the mushrooms — cook in batches if needed for proper caramelization
- Make ahead: assemble, cover and refrigerate up to 24 hours before baking
- Leftovers keep refrigerated up to four days and reheat beautifully with a splash of milk
