Soak amaranth grains overnight. In the morning, combine them with 2 cups of water in a saucepan. Bring to a boil, cover and cook on medium flame until tender, about 30 minutes. Keep aside.
In another saucepan, combine jaggery with ½ cup of water and cook till melted. Add cooked rajgira, red poha, milk, ground elaichi and dry fruit. Bring the mixture to a slow simmer and cook till poha is tender.
Serve warm or at room temperature or chilled.