Remove the green skin part and soft part with seeds in the pumpkin. Grate it and squeeze gently to drain the excess water. You can save this if you are worried about the nutrient loss.
Heat a heavy bottomed pan and add a tsp of ghee. Fry the grated pumpkin well for 2 minutes.
Add 1/4 cup water or the squeezed water from pumpkin and cook covered until soft and tender.
Mix and mash in between to ensure even cooking.
Add sugar and mix until it dissolves. Add saffron and continue cooking.
Keep stirring over medium flame. Add ghee little by little while you stir.
Once the halwa thickens, add edible camphor powdered and cardamom towards the end.
When you stir, you will see few tiny white spots appearing in the halwa, when you turn it. This is the right stage to switch off the flame.
Lastly fry cashew nuts broken into two in ghee until golden and add to the halwa.
Let the whole process be done in medium flame. Especially after adding sugar. Adding edible camphor and cardamom is to suppress the smell of pumpkin. So add generously. Make sure you grate the white pumpkin evenly otherwise will remain uncooked. Adding sugar after the white pumpkin gets cooked is must. If uncooked, after adding sugar it will never get cooked and becomes hard.