https://www.simplyrecipes.com/recipes/cheesy_tortellini_casserole/
Ingredients
1 1/2 pounds (24 ounces) prepared frozen cheese tortellini
Salt
12 ounces cremini or white button mushrooms, roughly chopped or sliced into 1/4-inch slices
1 tablespoon butter
3 cloves garlic, minced (about 1 tablespoon)
1 (28-ounce) can crushed tomatoes
1 large bunch Swiss chard, ribs removed, leaves chopped (about 2 cups), or 2 cups fresh chopped spinach, or 1/2 cup frozen spinach
1 1/2 teaspoons dried basil or 1 tablespoon finely chopped fresh basil
1/4 teaspoon fennel seeds, crushed
Pinch red pepper flakes
1/2 cup grated Parmesan cheese
4 to 6 ounces mozzarella cheese slices, enough to cover the surface of the casserole