In a mixing bowl, combine 500 grams of minced chicken, 1 finely chopped onion, 2 minced garlic cloves, 1 teaspoon ginger paste, 1 teaspoon red chili powder, 1 teaspoon garam masala, salt to taste, and 1 tablespoon chopped coriander leaves. Mix well and divide the mixture into 8 equal portions.
Shape each portion into a round patty, about 1 cm thick.
Heat 2 tablespoons of oil in a non-stick pan over medium heat. Cook the chicken patties for 4-5 minutes on each side, or until they are cooked through and golden brown. Set aside.
In a small bowl, mix together 4 tablespoons of mayonnaise and 2 tablespoons of tomato ketchup to make the burger sauce.
Slice 4 burger buns in half horizontally. Lightly toast the buns on a heated pan for 1-2 minutes.
To assemble the burger, spread a layer of the burger sauce on the bottom half of each bun. Place a lettuce leaf on top, followed by a chicken patty, a slice of cheese, another chicken patty, and another slice of cheese. Top with sliced tomatoes, onions, and another layer of the burger sauce. Finally, place the top half of the bun on the assembled ingredients.