Feta sold at most major supermarkets is generally made with cow’s milk, because it is cheaper, but it is SO much better to use one made with sheeps’ milk (as it is supposed to be!). They sell one at Trader Joe's, one in brine and otherwise you'll want to look at markets with larger cheese sections. One of my smart testers tried this with soft goats’ cheese in place of the cream cheese and loved it, so know that is a great swap if that is what you stock. Make this swap on the grocery list.