Preheat oven to 400°F (200°C) and grease a standard 12-cup muffin tin with non-stick spray or butter.
In a large skillet over medium-high heat, cook the ground sausage until fully browned and crumbled. Drain excess fat on paper towels.
In a large mixing bowl, whisk together flour, baking powder, salt, and black pepper.
In a separate bowl, whisk together the eggs, milk, and melted butter.
Pour the wet ingredients into the dry ingredients and stir until just combined; do not overmix.
Gently fold in the cooked sausage, shredded cheese, and green onions.
Distribute the batter evenly into the 12 muffin cups, filling each about three-quarters full.
Bake for 18 to 22 minutes until the tops are golden and a toothpick inserted into the center comes out clean.
Cool in the tin for 5 minutes before removing to a wire rack to serve warm.