Broccoli Casserole From Scratch

INGREDIENTS

2 1/2 lb

broccoli florets, cut into bite-size pieces (about 8 cups)

6 tbsp

butter, divided

1 cup

finely chopped crimini or button mushrooms

1/4 cup

flour

1 cup

milk (whole or 2% preferred)

1/2 cup

half and half

1/2 tsp

salt

1/4 tsp

freshly ground black pepper

1/2 cup

plain Greek yogurt

1 cup

finely chopped yellow onion

egg, lightly beaten

1 1/2 cups

grated cheddar cheese, divided

1 1/4 cups

whole-wheat breadcrumbs (homemade* or store-bought), divided