For an easy vegetarian twist on classic Italian comfort food, I substituted loads of mushrooms for chicken in this Baked Mushroom Tetrazzini!
Tetrazzini is baked pasta dish that usually uses a white cream sauce as a base. Sometimes it has chicken in it, but I think this mushroom version actually has more flavor – chicken can be a little bland sometimes in dishes like this.
This tetrazzini is a great baked pasta dish that is pefect for a chilly winter dinner.
Cooking the Mushrooms
I like to use a lot of mushrooms for this recipe. I kept it simple and just used cremini mushrooms but you could use a variety of mushrooms if you wanted.
You do need to cook the mushrooms before you add them to the tetrazzini. I like to do that with a mix of olive oil and butter in a large skillet with onions and garlic.
The mushrooms will cook down and reduce their volume substantially. When the skillet is dry, the mushrooms are sauteed, and the onions are soft, add some white wine to the skillet to deglaze the pan.
Okay! Let’s talk sauce!
Making the Tetrazzini Sauce
This sauce has a mix of milk, cream, and vegetable stock. It starts with a basic roux (flour and butter) much like a gravy recipe, but has much more liquid that you would normally use. The result is a thinner sauce that thickens as it bakes with the pasta.
To make the sauce, just whisk the flour and butter together in a medium sauce pan over medium heat. After a few minutes the flour should be a tan color. Then start whisking in your liquids slowly. Season the sauce and it’s ready to go.
I recommend stirring everything together in the baking dish you are using. Why dirty another pan, right?
Baking the Mushroom Tetrazzini
When you first add your sauce, it will look a little soupy. That’s okay. Don’t worry. It will thicken beautifully as it bakes.
To top the tetrazzini, I like to mix up a quick topper of parmesan cheese, bread crumbs, and fresh parsley.
Sprinkle that mixture all over the top of the mushroom tetrazzini.
Bake this whole thing at 400˚ F. for 20-25 minutes until it’s bubbling around the edges and the topping is crispy.
Extra Add-ins For Tetrazzini
There are a few add-ins that go well in this dish. You could, of course, add shredded chicken, which is a classic ingredient. Also, peas go well in it. You can stir in a cup of frozen peas if you wanted before baking the tetrazzini.
Storing and Reheating Mushroom Tetrazzini
The dish actually keeps and reheats pretty well. The best way to reheat it is in a 325˚ F. oven until it’s warmed through. You can microwave it in short bursts until warmed through as well.
Make some classic Italian comfort food this winter! This tetrazzini recipe is a keeper!
Baked Mushroom Tetrazzini
- 12 ounces spaghetti, cooked and drained
- 2 tablespoons butter
- 2 tablespoons olive oil
- 1 ½ pounds cremini mushrooms, sliced
- 1 small white onion, chopped
- 4 cloves garlic, minced
- ½ teaspoon kosher salt
- ¼ teaspoon black pepper
- ½ cup white wine
- ¼ cup butter
- ¼ cup all-purpose flour
- 3 cups whole milk
- 1 cup heavy cream
- 1 cup vegetable broth
- 1 teaspoon dried thyme
- 1 cup frozen sweet peas, optional
- ½ cup grated Parmesan Cheese
- ½ cup bread crumbs
- 2 tablespoons chopped fresh parsley
- Preheat oven to 400˚ F. Grease or spray with nonstick spray a 9×13 baking dish.
- To start mushrooms, add butter and olive oil to a large skillet over medium-high heat. Add sliced mushrooms, onions, and garlic. Season well with a pinch of salt and pepper and cook for 6-8 minutes until mushrooms have lost their liquid and are starting to brown in spots. When the skillet is completely dry, deglaze with white wine and use the wine to scrape up any stuck bits. Then remove from the heat.
- Meanwhile, cook spaghetti according to directions in salted water. Cook until al dente and taste frequently to be sure not to overcook it.
- To make sauce, add butter and flour to a medium pot over medium heat. Whisk together for 2-3 minutes, whisking the flour into the butter, forming a roux.
- When the roux is a light tan color, slowly whisk in the milk, cream and stock. Continue to whisk, bringing the mixture to a simmer. Simmer for 2-3 minutes to allow the sauce to thicken slightly. It should barely coat the back of a spoon and should not be as thick as a gravy. It will thicken more as it bakes.
- In a small bowl, stir together grated parmesan, bread crumbs, and fresh parsley.
- Transfer drained pasta to your prepared baking dish and stir in the mushroom mixture. Then add the sauce and mix everything together well. Season with salt and pepper.
- Top the baking dish with the parmesan mixture and bake at 400˚F. for 20-25 minutes until the casserole is bubbling and the parmesan topping is crispy and browned.
- Remove from the oven and let cool for a few minutes before scooping and serving.
- Leftovers keep great in the fridge for 5 days. Reheat in the microwave until warm or (better) in a 325˚ F. oven, covered with foil, until reheated.