Preheat & Prep: Heat oven to 375°F (190°C) and grease a 9x13-inch baking dish.
Cook Sausage: Brown sausage in a skillet, drain the fat, and set aside.
Make Batter: Whisk pancake mix, milk, egg, vanilla, melted butter, optional syrup, and cinnamon until smooth.
Assemble: Mix in sausage and cheese, then pour batter into the dish and spread evenly.
Bake: Bake for 28–35 minutes until golden and set.
Cool & Slice: Let rest 5 minutes before slicing and serving.