This easy jalapeños-Cheddar cornbread starts with a box of Jiffy mix. Use it to make one 8-inch pan of cornbread or about 6-standard muffins.
Stir corn muffin mix in a large bowl to remove any lumps. Add ⅓ cup milk and 1 large egg. Stir to combine. Scrape bottom and sides of bowl down with a rubber spatula. Add ½ cup shredded cheese and 2 tablespoons of chopped jalapeños. Stir until incorporated. Let batter sit for 5 minutes.
For Cornbread: Grease an 8-inch round cake pan with nonstick cooking spray. Spread batter evenly into the pan. Top with additional sliced jalapenos.
For Corn Muffins: Line 6 standard muffin cups with paper liners. Fill each cavity about ⅔ full. Place a sliced jalapeño on top of each muffin.