In a medium pan, brown breakfast sausage with 1/2 cup sweet peppers and the diced onion. Cook until sausage is cooked through and peppers and onions are soft. Drain and set aside.
The night before serving, grease a 9x11 baking pan. Cut the English muffins into 1 inch chunks and layer into the bottom of the pan. In a medium bowl, whisk eggs, milk, salt, pepper, and paprika. Pour over the English muffins. Sprinkle in sausage mixture. Top with cheese and additional diced pepper. Cover and allow to chill overnight.
In the morning, remove from the fridge 30 minutes prior to cooking. Bake in a 375 degree oven for 35-45 minutes, until a butter knife can be inserted and comes out clean.