In a heavy-bottomed saucepan or kadai, add the milk powder, milk, powdered sugar, pumpkin puree, ground cardamom, and one tbsp of ghee.
Mix it well without any lumps.
Over medium-low heat, cook this mixture. It will loosen up, and it will be slightly runny. And that's perfectly fine.
After about 4 to 5 minutes, the mixture will thicken, and at that stage, add the remaining ghee and mix well.
Now reduce heat further (on a number scale to 2 or 3) and cook the mixture for 8 to 10 minutes (timing might vary, please see the consistency check below) until it thickens. Please do not leave it unattended. Keep stirring at regular intervals.
Consistency check - When the milk powder mixture thickens, and it will come together as one mass. When you drop a blob of milk powder mix, it should fall without sticking in the spatula as shown in the picture; alternatively, you can take a small piece of the burfi mix and let it cool. If you can make a small ball without the mix sticking to your fingers, it is done. If not, cook again by adding little ghee.
Now transfer it to a plate or cake pan lined with parchment paper and spread it evenly or per the desired thickness. Sprinkle the nuts and rose petals and press them gently. Let it cool for 60 to 90 minutes. The slice the burfi and enjoy.
Notes
Use flavorings of your choice, but with pumpkin, I won't recommend rose flavor.
I did not test the recipe with freshly grated pumpkin. But you can very well grate the pumpkin finely and use it. In that case, cook the pumpkin first with ghee and water; add the sugar and milk powder when the pumpkin becomes soft and tender.
VVK Tips:
Like every other sweet recipe, I made this also in the stainless steel pan. As I mentioned in my thirupagam recipe, use a silicone spatula as it's easy to scrape the sides without any damage to the pan, and it also comes out clean.
I have used a minimal amount of ghee, but you can add one more tbsp extra.
Always cook on medium-low heat (on a number scale between 3 and 4) and stir the sweet regularly. Do not leave it unattended for too long.
Set the burfi on a plate lined with parchment paper.