Wash and soak the chana dal in sufficient quantity of water for about 3 to 4 hours or overnight.Drain and pressure cook the dal until soft.Strain the cooked dal to remove excess water.Allow to cool slightly.
Meanwhile,prepare the dough by mixing whole wheat flour,salt,vegetable oil/ghee and enough water in a large mixing bowl.Knead well to for about 3 to 5 minutes to form a smooth and soft dough.Cover and set aside for about 15 to 20 minutes.
Mash the cooked dal well using a potato masher or transfer to a blender/food processor and process to form a smooth paste.Transfer the dal into a heavy bottomed pan along with ghee and jaggery .Cook over medium heat stirring continuously for about 3 to 5 minutes until the mixture turns thick.
Allow to cool completely,add the cardamom and nutmeg powder and knead well.Divide this into 10 to 12 equal portions.Set aside until required.
Divide the dough into 10 or 12 equal parts and roll a portion of the dough into a circle of 4" diameter on a lighly floured surfce.Place a portion of the filling in the center.
Bring all the sides to the center and seal tightly.Flatten the ball and dip it in the flour.
Dust the working surface with whole wheat flour ,roll the stuffed dough lightly to form a 7 to 8 "circle.Lightly dust the poli with flour,if it sticks to the rolling pin or the working surface.Heat a tawa,place the puran poli and let it cook until the colour changes slightly for about 15 seconds over medium high heat. Flip the poli and let it cook for few more seconds.Drizzle 1 tsp ghee over the poli.Flip the poli again and gently press using a spatula.Cook until golden spots appear on both the sides.Repeat with the remaining dough and the filling.Serve with melted ghee and milk.
