Preheat oven to 375°F. While the oven is heating, put the bacon grease into a 10-inch cast-iron skillet and place it in the oven while the oven preheats.
Meanwhile, mix the cornmeal, flour, baking powder, and salt. Whisk together the eggs and buttermilk and pour into the dry ingredients. Add the jalapeño, onion, garlic, corn, and cheese, then stir until smooth and well combined.
Take the cast iron skillet out of the oven and pour the hot oil into the batter. Stir until well combined.
Pour the batter back into the hot skillet and bake for 30-35 minutes or until the top is lightly browned and an inserted knife comes out clean. Serve warm.
Notes
The cheese may give a false read when inserting the knife, so if the top and edges are set and lightly browned and the knife comes out with cheese on it, try inserting it in another spot to be sure it's good to go. If you want to add sugar, I'd start with a teaspoon.