Preheat oven to 400°F and lightly grease casserole dish with cooking spray.
In a cast iron skillet, brown sausage over medium heat until fully cooked. Drain grease and set aside.
In a medium mixing bowl, whisk flour, cornmeal, sugar, baking powder, and salt together.
Stir in melted butter (or reserved sausage grease), egg, and milk. Mix until smooth.
Fold cooked sausage and shredded cheddar cheese into the batter, along with any optional vegetables.
Pour mixture into the prepared casserole dish.
Bake casserole for 20 minutes, or until top is golden brown and cooked through.
Remove from oven, let cool slightly, and serve warm. Enjoy!