Baked Mushroom Tetrazzini

Serves 6.
Prep Time:
Cook Time:
Total Time:
Rated 0 out of 5
0 out of 5 stars (based on 0 reviews)
Very good0%
Baked Mushroom Tetrazzini
Print Recipe

Comfort food at its best! This baked Mushroom Tetrazzini has a quick homemade sauce, loads of sauteed mushrooms, and a crispy Parmesan topping. Perfect for a chilly winter night!


12 ounces spaghetti, cooked and drained
2 tablespoons butter
2 tablespoons olive oil
1 1/2 pounds cremini mushrooms, sliced
1 small white onion, chopped
4 cloves garlic, minced
1/2 teaspoon kosher salt
1/4 teaspoon black pepper
1/2 cup white wine

White Sauce:

1/4 cup butter
1/4 cup all-purpose flour
3 cups whole milk
1 cup heavy cream
1 cup vegetable broth
1 teaspoon dried thyme

Other Ingredients:

1 cup frozen sweet peas (optional)
1/2 cup grated Parmesan Cheese
1/2 cup bread crumbs
2 tablespoons chopped fresh parsley


  1. Preheat oven to 400˚ F. Grease or spray with nonstick spray a 9×13 baking dish.
  2. 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.
  3. Meanwhile, cook spaghetti according to directions in salted water. Cook until al dente and taste frequently to be sure not to overcook it.
  4. 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.
  5. 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.
  6. In a small bowl, stir together grated parmesan, bread crumbs, and fresh parsley.
  7. 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.
  8. 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.
  9. 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.