Every once in a while I make a Gratin, but I never get them to come out exactly like I want. Last time, I did a potato, parsnip, and fennel gratin with goat cheese, mozzarella, and fresh cream and it came out watery -- like the liquid separates from the veg and instead of becoming creamy and gooey, leaving the fat solids all that's between the layers. I'm thinking part of it was the mozz, which is watery and can separate when cooked, or that it might be water from the potatoes/parsnips cooking out. Does anyone else know of a solution? Cook at a lower temp? Use a specific cream/milk combo or thickener? Blanche the potatoes/parsnips first? I basically want it to come out creamy and cheesy and not separated, like the potatoes suck it all up and become really unctuous. Thanks for the advice in advance.