Spread butter on one side of both the bread slices. Top them with green chutney.
Top one of the bread slices with potato and sprinkle with little chaat masala. Layer with cucumber, beets, tomato and red onion (if using) and sprinkle each layer with some chaat masala.
Top with the cheese slices and the second bread slice. Press lightly and cut the sandwich into quarters or halves. Enjoy!!