Pre-heat the oven to 350° F.
Heat the bacon grease, or olive oil, in a large skillet over medium heat.
Then add in the garlic and sauté for 1-2 minutes.
Add the onion in with the garlic and sauté for another 2-3 minutes.
Add the ground beef into the skillet, stirring the onions and garlic into the meat. Cook on medium heat for 15 to 20 minutes, or until the meat is well cooked. Drain off any excess oil when the meat has finished cooking.
Mix the ketchup, Worcestershire sauce, and brown sugar into the meat, stirring until combined. Let this mixture simmer for at least 5 minutes.
Layer the sloppy joe meat in the bottom of the skillet or a 9x13 baking dish.
Next add a layer of corn.
Now add a good thick layer of mashed potatoes.
Finally, add the shredded cheese as the top layer.
Bake the casserole at 350° F for 20 to 30 minutes, or until the mixture is heated through and bubbly, and the cheese is melted.