Preheat the oven to 400 degrees F and spray an 8X8 baking pan with a non-stick cooking spray.
Heat a large skillet over medium-high heat. Add 1 pound ground beef, 1 diced red bell pepper, and ½ diced yellow onion.
Cook for 6–8 minutes, breaking up the beef as it cooks, until the beef is browned and the vegetables are tender. Drain any excess grease.
Stir in 1 teaspoon minced garlic, 1 (8-ounce) can tomato sauce, ½ cup ketchup, 2 tablespoons brown sugar, 1 tablespoon yellow mustard, 1 teaspoon Worcestershire sauce, and ½ teaspoon black pepper.
Bring the mixture to a low simmer and cook for 3–5 minutes, stirring occasionally.
Remove the skillet from the heat and spread the sloppy joe mixture evenly into the prepared baking dish.
In a medium mixing bowl, whisk together 1 package (8.5-ounce) Jiffy Cornbread Mix, 1 large egg, ? cup milk, and 1 tablespoon vegetable oil until combined.
Stir in 4 ounces (half) of the shredded cheddar cheese.
Spoon the cornbread mixture evenly over the sloppy joe mixture and carefully spread it to cover the surface.
Sprinkle the remaining 4 ounces shredded cheddar cheese over the top.
Bake for 25–30 minutes, or until the cornbread is golden brown and cooked through.
Remove from the oven and allow the casserole to rest for 5–10 minutes before serving.
Serve warm and enjoy.
Notes
Store leftovers in an airtight container in the refrigerator for up to 5 days.To make a double batch, use a 9x13-inch baking dish and increase the baking time as needed. Test the cornbread with a toothpick to ensure it is fully baked.