Preheat the oven to 350°F (175°C) and grease a muffin tin with olive oil or cooking spray. Set aside.
Cook the sausage: In a skillet over medium heat, cook the sausage until fully browned and crumbled, breaking it apart with a spoon as it cooks. Drain excess fat if necessary, then set aside to cool slightly.
Prepare the egg mixture: In a large mixing bowl, whisk together the eggs, milk, salt, pepper, garlic powder, and onion powder until well combined.
Add veggies and sausage: Fold in the cooked sausage, diced bell peppers, and onions (if using) into the egg mixture.
Fill the muffin tin: Spoon the sausage and egg mixture into each muffin cup, filling them about 3/4 full.
Top with cheese: Sprinkle shredded cheese evenly on top of each muffin.
Bake: Place the muffin tin in the preheated oven and bake for 18-20 minutes, or until the muffins are set and slightly golden on top.
Cool and serve: Allow the muffins to cool for a few minutes before removing them from the tin. Serve immediately, or store in an airtight container for meal prep.
Enjoy your Sausage Egg Muffins as a quick, delicious breakfast or snack!