Spread the bag of Fritos (1 bag) over the bottom of a 9X-inch baking dish. Spoon chili over the layer of Fritos. Sprinkle the red onion (1 cup) over the chili. Sprinkle top evenly with cheddar (2 cups).
Place baking dish under the broiler and cook until cheese is melty, about 5-7 minutes. Watch closely so the topping doesn't burn.
Spoon into individual plates or shallow bowls. Top with red onions, a dollop of sour cream, and sliced jalapenos. Serve!
Notes
Broiling: Traditionally cooks have always advised keeping the door slightly ajar when broiling in an electric oven to reduce the risk of fire. Ovens have changed quite a bit since their invention, however, and many operate just fine with the door closed. Some oven doors will not even stay open while the oven is operating! Check your manual to see the best practices for your oven model.