Preheat your oven to 350°F (175°C).
In a skillet over medium heat, cook the breakfast sausage until browned, about 5–7 minutes.
Add diced onions and bell peppers to the skillet, cooking until softened, about 3–5 minutes.
In a large bowl, beat together the eggs and milk, then season with salt, pepper, and oregano.
Stir in the cooked sausage, peppers, onions, and shredded cheese into the egg mixture.
Pour the mixture into a greased baking dish and bake for 30–35 minutes until set.
While the casserole bakes, prepare toast using the crusty bread.
Once the casserole is set, let it cool for a few minutes before slicing and serving.
