Step 1 — Melt the chocolate baseTake the milk, sweetened condensed milk, and chocolate chips together in a heavy-bottomed saucepan or non-stick pan. Turn the heat to medium-low.Cook, stirring continuously, until the chocolate chips are completely melted and the mixture is smooth, shiny, and uniform. This takes 3–5 minutes. Do not rush on high heat — chocolate scorches easily.Once completely melted, the mixture should look glossy and pourable. Remove from heat.
Step 2 — Add biscuit crumbsAdd the graham cracker crumbs to the chocolate mixture. Begin stirring to combine. When roughly half the crumbs are incorporated, add the chopped pistachios. Continue stirring until everything is fully combined and the mixture comes together into a soft, cohesive mass — like a very soft dough.At this point the mixture will be quite soft and sticky — this is correct. It needs to cool before it can be shaped.
Step 3 — Cool until shapeableTransfer the mixture to a plate or bowl and let it cool at room temperature for 15–20 minutes. It will firm up significantly as it cools. Test readiness by pressing a small portion between your fingers — it should hold together when pressed without feeling sticky or leaving chocolate on your hands.If the mixture is too soft: Refrigerate for 10–15 minutes until firmer. If the mixture has become too stiff and crumbly: Knead it briefly with warm hands — the warmth of your palms will soften it just enough to become workable again.
Step 4 — Shape using the mouldGrease the inside of your modak mould with a thin layer of ghee. Pinch off a portion of the cooled mixture — roughly the size you need to fill the mould. Before placing it in the mould, roll it into a smooth, tight ball between your palms. Press the ball firmly into the mould sides. Close the mould tightly and remove the excess from the sides.Open the mould and gently unmould the shaped chocolate modak onto a plate.Keep the shaped modak at room temperature if using within a few hours, or refrigerate until ready to offer.
Notes
Make-ahead for the full 10-day festival: Make a full batch on Day 1 or Day 2, refrigerate, and offer one or two each day alongside the other daily prasad. This is the most practical approach for a busy festival period.