Spread each slice of bread with butter on one side. Spread chutney over the butter. Sprinkle with chaat masala.
On one slice add the tomato and bell pepper slices. On the second slice, add the mashed potato and onion slices. Top both slices with the grated cheese.
Arrange the potato slice over the tomato slice (veggie sides up). Top the potato slice with the 3rd slice, chutney side down. Grill on a grill pan or use a sandwich maker. Its done when the cheese melts.
Serve with a spicy ketchup.