Cream of Mushroom Casserole

square crop of a cheesy topped casserole with noodles and mushrooms in a blue casserole dish and a serving spoon next to it.

4.96 from 25 votes

Cream of Mushroom Casserole

This Cream of Mushroom Casserole is the ultimate vegetarian comfort food! Loaded with creamy homemade mushroom soup, pasta, veggies, and cheese — it’s hearty, healthy, and family-approved. Perfect for cozy dinners or make-ahead meals!

Course Main Course

Cuisine American

Keyword casserole, cream of mushroom, mushrooms, pasta, vegetarian

Prep Time 20

Cook Time 30

Total Time 50

Servings servings

Calories 379kcal

Author Debi

Ingredients

Soup

2 tablespoons olive oil or light tasting oil of your choice, divided use
½ large onion finely chopped
6 ounces mushrooms finely chopped
½ teaspoon garlic powder
¼ cup all purpose flour
1 cup milk
¾ cup vegetable broth

Casserole

12 ounces small shape pasta like penne, shells, or Farfalle
½ teaspoon salt
½ teaspoon pepper
1 cup frozen peas thawed
1 cup shredded mozzarella cheese

Instructions

Make the soup

Heat 1 tablespoon oil in a saucepan over medium-high heat. Add onion and cook until onion has released its water and begins to brown, about 8-10 minutes, stirring occasionally.
2 tablespoons olive oil, ½ large onion
Add chopped mushrooms, and cook until mushrooms release their juices and the pan looks dry again, about 5-7 minutes.
6 ounces mushrooms
Add remaining tablespoon oil, garlic powder, and flour to pan. Cook for about 2 minutes.
½ teaspoon garlic powder, ¼ cup all purpose flour
Slowly add milk, stirring as you add so that there are no lumps. Add broth. Reduce heat, and cook for about 5 minutes longer, or until it reaches desired consistency. Season to taste with salt and pepper.
1 cup milk, ¾ cup vegetable broth

Make the casserole

Preheat oven to 375° F.
While soup simmers bring a large pot of salted water to a boil and cook pasta, cooking pasta for 1 minute less than the package instructions (pasta will continue to cook in the oven). Drain pasta, reserving about ½ cup of cooking water.
12 ounces small shape pasta
Stir cream of mushroom soup, salt, pepper, frozen peas, and ½ cup of shredded mozzarella together. Mix in the pasta. Mix in 2 tablespoons of pasta cooking water. If mixture seems too thick, or if you’re making casserole a day before for leftovers, stir in additional pasta cooking water 1 tablespoon at a time until desired consistency is reached. Taste for salt and pepper.
½ teaspoon salt, ½ teaspoon pepper, 1 cup frozen peas, 1 cup shredded mozzarella cheese
Place mixture in a casserole dish, and sprinkle remaining ½ cup shredded mozzarella over the top.
Bake casserole, uncovered, in 375° oven for 20-25 minutes, or until cheese is bubbly and browned a bit.

Notes

If you want to make this casserole in advance, add in a little extra pasta cooking water. The pasta soaks up the liquid as it bakes, and as it’s refrigerated. So, I like to add in a little extra moisture to keep things creamy.

To store, make sure to let the casserole cool completely, and cover it tightly with plastic wrap, or store it in an airtight container, and into the fridge for up to 5 days.

Reheat leftovers in the microwave or in a baking dish in a 350º F oven until warmed through, adding more broth to loosen up the casserole as needed. For longer storage, it can also be frozen for up to 3 months.

If you want to make it and not bake it, it’s a perfect meal to wrap up and send to a friend in need. Once you’re ready to bake it, let it thaw completely in fridge and bake as instructed per recipe.

Nutrition