Take milk, condensed milk and chocolate chips in a pan on medium-low heat. Let it melt and keep stirring to make sure that it is not sticking to the pan. It should be completely melted, shiny, smooth.
Now add graham cracker crumbs.
Start mixing and halfway through add chopped pistachios. Mix and it should come together like a dough-ball.
Remove it to a plate and let it cool to touch. Grease the modak mould using ghee. Keep the mould close. Stuff the small portion of it from the bottom hole. Then open the mould and gently unmould.
Repeat the same for rest.
Notes
Substitutes:
Graham cracker crumbs: Instead you can grind/crush any digestive biscuits or crispy vanilla flavored cookies or oreo cookies (without cream).
Chocolate chips: You can use the cooking chocolate bar, chopped up. To make dark chocolate modak, simply use dark chocolate here.
Pistachios: You can use your choice of other nuts like almonds, cashews, walnuts, hazelnuts, etc.
How to get the smooth surface unlike shown here(uneven)? Add ground powdered nuts instead of chopped. Also, take a portion, make a smooth, tight ball and then stuff into mould.Storage: It stays good for up to 4-5 days in the refrigerator in an airtight container.