Roast sesame seeds, poppy seeds, watermelon seeds, pumpkin seeds, and flax seeds in a nonstick pan/ kadhai over a medium burner, swirling constantly, until lightly toasted, and set aside in a big bowl.
Roast the peanuts and walnuts for 2-3 minutes on low heat, then set them aside in the same bowl.
To make a smooth paste, melt ghee in a pan, then add jaggery and water and stir to combine (takes about 3 - 4 minutes). Once the jaggery has dissolved, reduce the heat to low and simmer for another 2 - 3 minutes.
Stir in the roasted seeds-nuts mixture until everything is combined into a smooth, thick mass. Over a low flame, stir everything together for 2 minutes, then remove from the heat.
Pour the mixture in a greased tray or thali. Cut into cubes with a greased knife. Allow to cool before making pieces. Store in a cool dry container