Sieve the besan flour (chickpea flour), make sure there is no lumps, keep it aside.
Heat 1/2 cup of ghee in a pan and add the sieved besan flour.
Keep in low heat and mix the flour very well with the ghee, if any lumps are formed you can break them using a good quality spatula, this is important since we need a smooth texture for the halwa.
Roast the mixture in low heat for few minutes (you need to keep stirring) until the mixture starts to turn color. Roasting the flour is so important or the halwa won't taste good. Roasting the besan flour for halwa can take a few minutes and the time may depend on the flour you use. For me, it took around 8 to 10 minutes in low heat. Tip: The flour can quickly burn so if you think its changing colors too fast before its roasted, you may switch off the stove and give a little time to cool down the mixture a little while you keep stirring the mixture, and then roast again in low heat until the flour is roasted enough.
Once the flour mixture is roasted, add the cardamom powder and mix well.
Add the water, mix well (break any lumps that may form using the spatula) and cook the mixture for 2 to 3 minutes, stirring frequently, until the flour is cooked well and the water is almost absorbed.
Add the sugar, mix well and cook in low heat (while stirring) for another 2 minutes or until the mixture starts leaving from the sides of the pan.
Add one teaspoon of ghee and cook for another 1 minute, stirring frequently.
After one minute, add the next spoon of ghee also and cook for another 1 more minute. Now the delicious and easy besan ki halwa is ready, though you may cook for more time if you wish to reach your preferred consistency.
Transfer the halwa to a serving dish, garnish with chopped nuts, serve hot or warm! You may also refrigerate the halwa and serve it later as you wish.