Tater Tot Breakfast Casserole

Name: Tater Tot Breakfast Casserole
Ingredients: Unsalted butter, for the baking dish; 1 16-ounce bag frozen Tater Tots; 1 tablespoon olive oil; 1 pound loose spicy breakfast sausage; 1 onion, finely diced; 1 cup whole milk; 1/2 cup half-and-half; 1/4 teaspoon seasoned salt; 1/4 teaspoon cayenne pepper; 4 large eggs; 1 red bell pepper, finely diced; 1 green bell pepper, finely diced; 2 cups grated cheddar cheese; 1 cup grated pepper jack cheese; Kosher salt and freshly ground black pepper