Mix the mayonnaise, ketchup, and garlic chutney in a small bowl.
Spread green chutney on one slice of bread and the mayonnaise mixture on the other.
Add the fienly chopped red onion, red bell pepper, green bell pepper, and jalapeños to one slice.
Sprinkle chaat masala over the vegetables.
Add the shredded mozzarella and cheddar cheese.
Add a small dollop each of green chutney and mayo. sprinkle little bit of chaat masala over the cheese.
Close the sandwich with the second slice of bread, keeping the spreads on the inside.
Butter the outside of the sandwich or melt a little butter in a skillet.
Cook over medium-low heat for 3–5 minutes per side, until golden brown and the cheese has melted.
Slice and serve hot.