In a small bowl, whisk together eggs, milk, salt, and pepper until well combined.
Heat a non-stick skillet over medium heat. Add the sausage and cook, breaking it up with a spatula, until browned and cooked through, about 4-5 minutes.
Remove sausage from skillet and set aside. Drain excess fat if necessary.
Reduce heat to medium-low. Add butter to the skillet and let melt. Pour in the egg mixture and let it set for about 30 seconds without stirring.
Using a spatula, gently push the cooked eggs from the edges toward the center, tilting the pan to allow uncooked eggs to flow to the edges. Continue until eggs are mostly set but still soft and moist.
Return the cooked sausage to the skillet and stir gently to combine. If using cheese, sprinkle over the top and let melt for about 30 seconds. Serve immediately.
Tips
For extra flavor, use spicy or maple breakfast sausage.
Serve with toast or hash browns for a complete meal.
Leftovers can be stored in the refrigerator for up to 2 days; reheat gently in the microwave.