Stir crushed hazelnuts into the chocolate-hazelnut spread until you have a thick paste.
Scoop about ½ tsp paste, place one whole hazelnut in the middle, and roll into a tight ball. Repeat for 10–12 balls.
Freeze on a plate for 10 minutes while you make the shell.
Cook the chocolate-coconut dough
Warm ghee in a small pan over low heat. Add desiccated coconut and stir 2 minutes until fragrant.
Whisk in cocoa powder, then pour in condensed milk. Keep heat low and stir constantly 3–5 minutes until the mix thickens and gathers into a soft dough ball.
Transfer to a plate and cool until comfortable to handle. The dough should feel like playdough, not sticky syrup.
Shape the modaks
Brush the inside of a modak mold lightly with ghee.
Take a walnut-sized piece of dough. Press it along the mold walls, leaving a hollow center and an even rim at the opening.
Place one chilled filling ball in the hollow. Pinch a small flat piece of dough to cover the base and seal tightly.
Open the mold carefully and ease the modak out. Repeat with remaining dough and filling.
Serve
Chill 15–20 minutes for a firmer bite, or serve at room temperature the same day.
Notes
If the shell cracks while demolding, patch with a smear of warm dough and chill again.For a nut-free version, use sunflower seed butter and skip whole hazelnuts; shape smaller centers so the mold does not tear.Vegan swap: use coconut condensed milk and a dairy-free chocolate spread; add 1 tbsp coconut oil when cooking the shell for pliability.Store in an airtight container in the refrigerator up to 4 days. Bring to room temperature 10 minutes before serving so the shell softens slightly.