Preheat your oven to 350°F (175°C).
Cook the sausage: In a skillet over medium heat, crumble and cook the sausage until no longer pink. Drain excess fat.
Prepare pancake batter: In a bowl, combine pancake mix, milk, eggs, sugar, vanilla extract, and baking powder. Stir until well blended.
Combine: In a greased baking dish, spread the cooked sausage evenly. Pour the pancake batter over the sausage.
Bake: Place in the oven and bake for 25-30 minutes or until the casserole is golden brown and a toothpick inserted into the center comes out clean.
Serve: Once out of the oven, let it cool for a few minutes before slicing. Serve warm with your choice of toppings!