To being with, blanch the almonds and soak them in hot water for about 10 minutes. After that, peel the skin of the almonds and keep aside to make the Thandai.
Now add the blanched almonds, cashew nuts, pistachios, cinnamon, fennel seeds, cardamom, black pepper and poppy seeds into a blender and blitz into a fine powder.
Add 1/4thcups milk and grind the dry fruits into a fine paste. (You can also make extra and store it in the refrigerator to make Thandai anytime).
Now, in a heavy bottom saucepan, add milk and saffron and bring the milk mixture to a boil.
As the milk begins to boil, add sugar and put it on simmer stirring continuously till the sugar dissolves.
Add the boiled saffron milk in the Thandai spice mixture, give it a good stir and leave it on simmer for another 5 minutes.
Now turn off the heat and allow the Thandai to completely cool down so you can place it in the refrigerator.