Steps

1. Preheat the oven to 400 degrees.
2. For the crust, put the flour, salt, baking powder, sugar, and butter in a food processor and process for a few seconds, until the mixture resembles soft, fresh breadcrumbs. Tip into a bowl.
3. Pit, skin, and slice the peaches, dropping the fruit into a 9-inch round oven-safe dish. Toss in the blueberries, lemon juice, sugar, and flour. Combine.
4. Mix the sour cream into the cobbler crust mixture. You will have a soft dough. Break off walnut-sized pieces, flatten them lightly, and lay them on top of the fruit. Dust the rounds of dough with sugar, then bake for 25 minutes, until the cobbler is golden and the fruit is bubbling.