Wash the mutton mince thoroughly and drain. Wash and soak the chana dal for half an hour. Add chana dal, cardamoms, cinnamon, cloves, one cup of warm water and salt to the mince and cook till dry.
Remove from heat and add chopped ginger, chopped garlic, red chilli powder, garam masalas powder, peppercorns, coriander powder and cumin powder. Cool and grind to a fine paste and knead well. For stuffing mix together finely chopped onion, chopped mint leaves, chopped coriander leaves, lemon juice and salt to taste.
Divide the mutton mixture into lemon-sized balls, flatten each ball in the palm of your hand and stuff with a little of the onion mixture. Shape into kababs and dip in the beaten egg. Heat a tawa and shallow fry the kababs on both sides with ghee till golden.
Drain onto an absorbent paper. Apply butter and green chutney liberally on all the bread slices on one side only. On a flat board, arrange four bread slices with the buttered and chutneyed side up. Layer each slice with lettuce leaves, two shammi kebabs pressed lightly with hands and few slices of tomato.
Top it up generously with mozzarella cheese and finally sprinkle chaat masala. Cover each one of them with another slice of bread with the buttered side down and press it lightly.
Toast each sandwich in a sandwich toaster on either side, applying butter to the exposed side of the bread slices. Remove when golden brown. Serve hot with tomato ketchup.