I've never made cheese . Looks like the Paneer I was thinking of experimentally making could work with UHT .
I don't want to discourage you Cos because I think Paneer is a brilliant type of cheese.
Apart from the taste, what I like most about Paneer is that it only takes 30 mins to make from scratch and it is bone-simple to make, but not with UHT milk.
The weblink below explains it all - how Paneer is what is known as a 'fresh' cheese - (which simply means you can make it and eat it the minute it is made — there's no endless hanging about while it spends months of ageing in dank underground caverns. Absolutely no ripening or ageing is needed - you only have to press the curds under a weight for 15 minutes or so.)
You'll find a very good recipe for making your own Paneer cheese on this weblink below if you scroll down a fair way...
https://www.thekitchn.com/how-to-make-paneer-cheese-in-30-minutes-cooking-lessons-from-the-kitchn-57008It's a good site - and it basically says that (apart from milk, lemon juice or vinegar and a pinch of salt) you only need a pot, a strainer, and some cheesecloth.
But, here's the bad news. This site says quite categorically....
"Also avoid using ultra-high temperature (UHT) pasteurized milk, as this pasteurization process changes the protein structure of the milk and prevents it from separating. Unfortunately, labels don't always make it clear when milk has been UHT pasteurized. If your milk won't separate into curds and whey, there's a good chance it was UHT pasteurized. "
It's so easy to make Paneer because when you mix the right milk with the lemon juice together, the acidity in the lemon juice will immediately cause the milk to 'curdle' or separate into curds and whey.
You then just ladle off the whey and press the remaining curds in any old cheesecloth shirt you have lurking about and - bingo, you have got a very good basic cheese.
Just remember to leave your UHT milk in the cupboard even for Paneer - maybe for a 'Ricotta type' cheese it'll work well enough though?