To work with whole emmer wheat: The day before you want to prepare the halva, soak the wheat in a good amount of water for about 6-8 hours. That evening, grind the wheat with about 4-5 cups of the soaking water. You should have a thinnish liquid at the end. Set this in a dish, covered, and leave it to ferment overnight.
To work with flour: The evening before you want to prepare the halva, soak the emmer wheat flour in 4 cups of water and leave it to ferment overnight.
The following morning: extract the wheat milk by filtering it through a cheesecloth. You may need to stir and coax the milk out, but don’t press too hard or you’ll end up pressing through a lot of the wheat solids, too. Discard the solids.
Prepare a rimmed plate, cake pan, or other baking dish to set the halva. You can simply use ghee to grease it, or line it with greased parchment or a greased banana leaf. Set this aside.
If you have not prepped the coconut milk yet, do so now. Scrape the coconuts, and blend with 2 cups of water or a little more. Extract the first milk: this will be rich and thick. Return the coconut solids to the blender with 2 more cups of water and repeat the milk extraction. Do this again a 3rd time for a total of about 1.5 litres or 6 cups of both thick and thin coconut milk.
If you’ve not prepped the panavella-paakam, do so now. Crush the jaggery and heat it with the water in a saucepan. Mix so the jaggery melts and heat until you see signs of bubbling at the sides. Turn off the flame and allow to cool.
In a separate, heavy-bottomed vessel, combine the fermented wheat milk and about half the coconut milk. Bring to a gentle simmer, mixing to ensure the mixture doesn’t clump as it begins to cook. Add the white sugar and mix well to dissolve. I find it easier to use a whisk at this stage, and to switch to a spatula as the mixture thickens later.
Now add the remainder of the coconut milk and continue to heat gently. The mixture will start to thicken fairly soon. Depending on the heat and quantity of liquid, this may happen slowly—this is good, because it allows you to control texture and prevent lumping easily.
Once the mixture is thickening, slowly pour in the panavella-paakam or toddy palm jaggery syrup. Taste mid-way if you like: if the fermentation of the wheat has been more or less, this is your chance to adjust sweetness. Keep in mind, however, that the sour taste mellows on cooking, so resist the temptation to add much more jaggery syrup. 1 cup white to 1 cup palm jaggery is usually just perfect, and less (preferably less white sugar, not less panavellam or karupatti) is ok, too.
Continue mixing, don’t leave the mixture unattended for more than a short arm break or it will cook at the bottom and make the halva texture hard to keep consistent.
After what feels like an interminable time (about 30-40 minutes), the halva will start to look more solid. It will have reached a mud-pot volcanic boil, and the bubbles will have gone from small to quite large, owing to the glutinous quality of the wheat. You’ll be able to scrape and see the sides of the pan for a couple of seconds as the halva will be viscous and won’t flow as quickly as before.
Keep mixing a few minutes longer and then start adding the ghee. Do this in stages, about ¼ cup each time, to have better control of how much you use. In my experience, you will need a minimum of ½ cup, but how much beyond that is up to you. The better halvas always have more rather than less ghee added, the mixture should look rich and glossy and be pulling away from the sides of the pan, with some visible signs of ghee oozing from the sides.
At this stage, switch off the flame. Add the flavorings and roasted-crushed cashews (or press the cashews into the surface of the halva at the next step).
Allow the halva to cool in the pan for a few minutes, then tip it out into the prepared pan or dish. Let the halva rest and cool completely before cutting into pieces and serving.
Tirunelveli muscoth is best served warm or at room temperature, the same day. You can store this at room temperature for a few days, or refrigerate for longer. To revive refrigerated halva, heat very lightly in a microwave or convection oven & serve.