The cooking time for the Urad dhal will depend on the process of cooking. If you're using a pressure cooker, it's almost done before the first whistle. If you're just boiling it in a pot, cover it and cook for about 20 mins.
Drain most of the water.
Process the urad dhal till it forms a puree. Cool
In a food processor with a dough attachment add the rice flour, hing, salt, chilli powder, chilli flakes and the butter.
Add the pureed Urad dhal a little at a time forming a nice dough
You shouldn't need any additional water but if your dough is dry, add a little bit.
Add to a Chakli press and in a clockwise or anti clockwise motion start spiraling on a piece of parchment paper.
Fry in hot oil for a few minutes.