This genre of traditional Thai desserts where something is cooked in sweetened coconut cream (kaeng buat) is arguably the most homey and heartwarming of all. It's like a hug in a bowl. This hug is pretty easy to make too. There's really nothing to it. I even feel a little embarrassed giving you a recipe when perhaps none is needed.
The good news doesn't stop here: once you've understood how this works, you can make any kind of kaeng buat. In other words, you know how to make one dish in this dessert family, you know how to make them all. We've chosen pumpkin today for our kaeng buat. It's one of the most common kaeng buat ingredients and, in my opinion, one of the most delicious. But it doesn't have to be pumpkin if you don't like pumpkin. Regardless of your main ingredient, the process is the same.
First pick a thing to make kaeng buat out of, such as yam, taro, or banana. Pumpkin, therefore, works perfectly well here. Traditionally, one ingredient is used instead of a melange of things. I guess this is because you won't have to deal with multiple ingredients which cook at different rates.
After you've picked your main ingredient, prepare it in such a way that each piece can be easily consumed in one bite (or two at the most) without a lot of fuss. That is to say, if your ingredient needs to be peeled, peel it; if it needs to be deseeded or pitted, do that, if it needs to be cut into bite-sized chunks, proceed accordingly. Then you put those bite-sized chunks in a pot and add just enough coconut milk to cover them.
Cook them gently over medium heat to keep the coconut cream from splitting. (If this was a curry, things would be different and you would want to 'crack' the coconut fat as I have explained in my earlier post on salmon-fennel red curry.) As the ingredient is being cooked, add some granulated or palm sugar (or a combination of both) as well as a tiny pinch of salt. Once it's cooked, taste the coconut cream to see whether it's sweet enough, then adjust seasoning accordingly before taking the pot off the heat. I always add less sugar than I think prudent, then add more as needed.
Kaeng buat can be served warm, at room temperature, or cold.