Preheat the oven to 350 degrees F (180 degrees C).
Whisk eggs with milk, salt, pepper, and garlic powder in a bowl. Set aside.
To a 10-inch cast iron skillet over medium heat, add sausage, onion, and bell pepper. Cook, stirring often, until sausage is browned and crumbled and vegetables are soft, about 10 minutes. Drain oil from the skillet and return it to the stove.
Add eggs to the skillet and cook, stirring, until eggs are set, 3 to 5 minutes. Remove from heat and stir in half the shredded cheese. Place biscuits on top of egg and sausage mixture, then sprinkle with remaining cheese.
Bake in the preheated oven until the biscuits are cooked and golden, 15 to 20 minutes.
