I've been making these delicious little savory pies from the Moosewood Cookbook -- they're little circles of pastry dough stuffed with a mashed potato/ cabbage/ cheese mixture, folded over and baked. Alas, while they bake, the filling explodes and runs all over the tray -- sometimes it happens at the seam or side, sometimes from the top. I tried pricking the tops with a fork to create steam vents, to no avail. Am I over-stuffing them? They don't seem THAT full. Does anyone have any other suggestions? I've made two batches now and am growing frustrated. I don't mind a little leaking, but they're currently like Mount Vesuvius (see photo). Thank you so much!