Preheat the oven to 350°F (175°C).
In a large skillet, cook the crumbled breakfast sausage over medium heat until browned.
Add the diced onion and bell pepper to the skillet and cook until softened.
In a large mixing bowl, whisk together the eggs and milk until well combined.
Stir in the cooked sausage mixture, diced potatoes, and half of the shredded cheese.
Season with salt and pepper, adjusting according to personal taste.
Pour the mixture into a greased 9x13-inch baking dish and sprinkle remaining cheese on top.
Bake in the preheated oven for 45-50 minutes or until the center is set and the top is golden brown.
Allow it to cool slightly before slicing and serving.