Ok, so peaches are gorgeous right now and I decided to make a peach galette for dessert last night. I used a sour cream pastry recipe (which I've used many times. It turns out a bit like a rough puff pastry - great for strudel) for the crust and white peaches for the filling. Rolled out the dough, heaped the peaches (lightly sweetened and mixed with cornstarch to thicken the juice) in the middle and turned the sides up around the edges. Ten minutes later I checked the oven and discovered - to my horror - that the sides had unfolded themselves onto the baking sheet and the peach filling was running all over the pan, and threatening to flow over the sides. I quickly pulled the mess out of the oven and rescued the filling by scraping it into another baking dish and topping it with a crumble mixture - turning it into a peach crumble instead. It was fine - delicious, in fact. But it was not a galette. What did I do wrong? Any ideas? Could the white peaches have been too juicy (yes, they were very very juicy)? Was the pastry too soft? What???