Finely chop 1 medium-sized onion, 1 medium-sized tomato, 1 small capsicum, and 1 green chili. Grate 200 grams of processed cheese or paneer.
In a mixing bowl, combine the chopped vegetables, grated cheese, 1/2 teaspoon chaat masala, 1/4 teaspoon black pepper powder, and salt to taste. Mix well to form the sandwich filling.
Take 8 slices of bread and evenly spread butter on one side of each slice.
Place a generous amount of the prepared filling on the buttered side of 4 bread slices. Cover each with the remaining 4 slices, buttered side down, to form sandwiches.
Preheat a sandwich maker or a non-stick pan. Place the sandwiches in the sandwich maker or on the pan and cook until they turn golden brown and crispy on both sides.
Once cooked, remove the sandwiches from the sandwich maker or pan and cut them into halves or quarters.