Easy Make-Ahead Breakfast Casserole

uncooked sausage, casings removed1

optional: 1 teaspoon dried rosemary to give the sausage more flavor

bell peppers, diced (any color you prefer; about 2 cups)

sliced mushrooms

fresh spinach

medium yellow onion, diced

minced garlic

salt and fresh ground black pepper

slices day-old gluten free bread (or whole wheat, white, sourdough, etc)

large Eggland's Best eggs

milk (I use almond milk, any milk works)

shredded cheese2