Dissolve coffee powder in 12 tablespoons lukewarm water to make a decoction.
Put cardamom seeds in the decoction and let the flavour infuse.
Add 1 cup milk in a cocktail shakes alongwith some ice cubes, one part of decoction and 2 tablespoons sugar syrup. Shake well. This will make frappe for one glass. Similarly make frappe for remaining 3 glasses.
Place lots of ice cubes into 4 individual tall glasses and pour the frappe in each glass. Serve chilled.