Wash, dry and peel the carrots using a vegetable peeler. Grate the carrots using a box grater or use food processor to grate the carrots. I use a food processor jar fitted with grater blade. Do not grate the carrots too fine else the halwa will not have any texture and it become mushy..
Choose a wide utensil for cooking carrot halwa if possible(read below why). Add a tablespoon of ghee to a heavy bottom kadai or skillet. Fry the chopped nuts for a few minutes in ghee and take them out in a plate.
Add 2 tablespoon ghee and add the grated carrots. Roast the carrots in ghee for 5-7 minutes while stirring constantly on low flame. This gets them started.
Next, pour in the hot milk. We will now cook them together on low heat for about 20-30 minutes or until 95% of the milk has evaporated and carrots are super soft. Using a spatula, keep stirring the the carrots and milk while they are cooking on low medium flame. This is to make sure that nothing is sticking to the bottom. You can half- cover the pan to help carrots soften if you wish.
Once most of the milk has evaporated and the carrots are soft, add in the sugar. As sugar dissolves, you will notice the carrots will again become runny. We will continue to stir and let moisture evaporate. Keep stirring at regular intervals and allow slow cooking till ALL the liquid has evaporated. During this time, do not increase the heat and keep a close eye since due to caramelization of sugar, the chances of carrots burning are high.
Once all moisture is gone, next, add the ghee and start the bhunai on low medium heat. Bhuno(fry) the carrots in ghee for a good 8-12 minutes on medium low heat. This is the key step for a nice toasty taste in the halwa. The carrots will become shiny, and you will smell a very very nice aroma. Please don't rush this part.
Once the bhunai is nearing completion, you will see that tiny ghee bubbles on the sides of cooking pot and you will also hear a faint crackling sound. Halwa is ready.
Switch off the stove and mix in the cardamom, crumbled mawa and the chopped nuts.Combine with gentle hands. Carrot halwa is ready. Avoid bhunai after adding the khoya else the fats from the mawa will separate and the halwa will become oily. The residual heat is plenty for the khoya crumbles to meld.
Serve warm garnished with extra chopped nuts. You can crumble extra khoya on top before serving.