In a large skillet over medium heat, add the breakfast sausage and cook for about 6-8 minutes until browned. Transfer to a paper towel-lined plate to cool.

In a mixing bowl, combine flour, cornmeal, sugar, baking powder, baking soda, and salt. In another bowl, whisk together egg, buttermilk, oil, and vanilla. Pour wet ingredients into dry and mix gently. Fold in sausage and cheese.

Preheat oven to 375°F (190°C) and prepare a muffin tin by greasing the cups.

Spoon the batter into the prepared muffin tin, filling each cup about 2/3 full. Bake for 15-20 minutes until a toothpick inserted comes out clean.

Cool in the tin for 5 minutes before transferring to a wire rack. Serve warm with maple syrup.