Preheat the oven to 375 degrees F. Grease a 12-cup muffin pan with cooking spray, and set it aside.
Cook the sausage in a skillet over medium-high, breaking it up into crumbles until it is no longer pink and cooked through. Drain the sausage on a paper towel-lined plate or bowl.
8 oz Breakfast sausage
In a large bowl whisk together the all-purpose flour, baking soda, baking powder, dry mustard, garlic powder, kosher salt, and black pepper.
2 cups All-purpose flour, 1/2 tsp Baking soda, 2 tsp Baking powder, 1/2 tsp Dry mustard, 1 tsp Garlic powder, 1/2 tsp Kosher salt, 1/2 tsp Black pepper
Beat the eggs in the measuring cup with the buttermilk.
2 large Eggs, 1 1/4 cup Buttermilk
Add the buttermilk, eggs, and melted butter to the dry ingredients and stir just until combined.
6 tbsp Unsalted butter
Add the cooked sausage, shredded cheese, and diced chives. Stir just until incorporated, do not overmix.
1 cup Sharp cheddar cheese, 1 tbsp Fresh chives
Divide the sausage muffin batter evenly among the prepared muffin tin. Sprinkle the tops of the muffins with additional shredded cheddar cheese if desired. Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool slightly before removing them from the muffin tin. Cool on a wire rack.