01 - Preheat the oven to 350°F. Grease a 9x13-inch baking dish with butter or nonstick spray.
02 - In a large skillet over medium heat, cook the breakfast sausage, breaking it up with a spoon, until browned and cooked through, about 5–7 minutes. Drain excess fat if necessary.
03 - Add the chopped onion and red bell pepper to the skillet. Sauté for 3–4 minutes until softened. Remove from heat.
04 - In a large bowl, whisk together the eggs, milk, melted butter, salt, black pepper, smoked paprika, and garlic powder.
05 - Gently fold in the biscuit pieces, cooked sausage mixture, and half of both cheeses.
06 - Pour the mixture evenly into the prepared baking dish. Sprinkle the remaining cheddar and Monterey Jack cheese over the top.
07 - Bake for 35–40 minutes, or until the center is set and the top is golden brown. If desired, broil for 2–3 minutes for extra color.
08 - Let rest for 5 minutes before serving. Garnish with sliced green onions if desired.