Preheat and prep: Heat oven to 350°F (175°C). Lightly spray a 12-cup muffin pan or line with parchment liners.
Cook the sausage: In a skillet over medium heat, cook turkey sausage until browned and cooked through.
Break into small crumbles and set aside to cool slightly.
Mix dry ingredients: In a large bowl, whisk flour, protein powder, baking powder, baking soda, and salt until combined.
Mix wet ingredients: In another bowl, whisk egg, egg whites, Greek yogurt, milk, maple syrup, vanilla, and oil until smooth.
Combine gently: Pour wet into dry and stir with a spatula until just combined. The batter should be thick but scoopable. If too thick, add 1–2 tablespoons more milk.
Layer the muffins: Add about 1 tablespoon of batter to each muffin well.
Sprinkle a small pinch of sausage over each, then cover with more batter until cups are about 3/4 full. Top with any remaining sausage. If using cheese, sprinkle a little on top.
Bake: Bake 15–18 minutes, or until tops spring back and a toothpick comes out mostly clean (a few moist crumbs are fine).
Rest and release: Cool in the pan for 5 minutes, then transfer to a rack.
This helps set the crumb and keeps them tender.
Serve: Drizzle with a tiny bit of warm maple syrup or a swipe of light butter. They’re great plain, too.