Preheat oven to 375°F. Lightly coat a 12-cup muffin tin with nonstick spray.
Cook the sausage in a skillet until browned and crumbly. Drain and let cool slightly.
Whisk flour, baking powder, sugar, and salt in a large bowl.
In a separate bowl, whisk milk, eggs, and melted butter until smooth.
Pour wet mixture into dry ingredients. Stir gently until just combined; a few small lumps are fine.
Fold in the cooked sausage and cheddar, if using.
Divide batter among muffin cups, filling each about 3/4 full.
Bake 14–17 minutes, until tops are golden and a toothpick comes out clean.
Cool in the pan 5 minutes. Release edges and serve warm with maple syrup.