Preheat your oven to 350°F (175°C). Grease a 12-cup muffin tin with non-stick spray or a light brushing of butter or oil to prevent sticking.

Place a skillet over medium heat and add breakfast sausage. Cook, breaking it up with a spatula, until browned and 160°F, about 5-7 minutes. Remove any excess grease.

In a large bowl, crack the eggs and whisk until combined. Stir in shredded sharp cheddar cheese and Bisquick baking mix until a smooth batter forms. Fold in the cooked sausage, distributing it evenly.

Divide the batter evenly among the 12 muffin cups, filling each about two-thirds full to allow room for rising.

Place the muffin tin in the preheated oven and bake for about 20 minutes, until the tops are golden brown, a toothpick inserted into the center comes out clean and the centers reach 160°F.

Let the muffins cool in the tin for a few minutes, then transfer to a wire rack or serve warm.