Preheat your oven to 175 °C (350 °F).

Butter a 9×13-inch baking dish and spread the cubed bread evenly in the bottom.

Sprinkle the cooked sausage and shredded cheese over the bread.

In a bowl, whisk together the eggs, milk, salt, and pepper until smooth.

Pour the egg mixture evenly over the layered bread, sausage, and cheese.

Gently press down so the bread soaks up the liquid.

If you like, sprinkle diced bell peppers or green onions on top.

Bake uncovered until the casserole is set in the center and golden on top, about 35–45 minutes.

Let it rest for 5 minutes before cutting and serving.