If you are planning to do an SP day, you need to make sure you pick the flavoured Quark, rather than looking for a protein yogurt. Protein yogurts are high in protein so they will help you feeling full, but they are still a yogurt.
Quark is a P food, so is therefore acceptable on an SP day.
They aren't a hex choice, but the Arla Protein ones are only 1 syn each and I really enjoy them with a stack of berries on top - perfect SP meal
Lidl make their own version, and they are a little cheaper, although I've not had any of them yet because I always forget to go into Lidl
The Skyr ones are tasty, and fine on any EE day, just not for SP
