In a mixing bowl, combine 500 grams of minced chicken or beef, 1 finely chopped onion, 2 minced garlic cloves, 1 teaspoon of salt, 1/2 teaspoon of black pepper, and 1/2 teaspoon of red chili powder. Mix well to form the burger patties mixture.
Divide the mixture into 4 equal portions and shape them into round patties, about 1 cm thick.
Heat 2 tablespoons of oil in a non-stick pan over medium heat. Cook the patties for 4-5 minutes on each side, or until they are cooked through and have a nice brown crust.
Place a slice of cheese on top of each patty during the last minute of cooking, allowing it to melt slightly.
Lightly toast 4 burger buns by placing them on the pan for about 1 minute.
Assemble the double cheeseburgers by placing a lettuce leaf on the bottom half of each bun, followed by a cooked patty with cheese, a slice of tomato, and a dollop of mayonnaise. Place another patty with cheese on top, followed by another dollop of mayonnaise, and finally, the top half of the bun.