In a large bowl, mix together the flour, sugar, salt, and baking powder.
Using a pastry cutter or your fingers, cut the cold butter into the flour mixture until it resembles coarse sand.
Pour the milk into the bowl and stir with a fork until the dough comes together in a rough ball.
Turn the dough out onto a lightly floured surface and gently knead it a few times until it comes together in a smooth ball.
Pat the dough out until it is about 1/4 inch thick. Using a biscuit cutter or the rim of a glass, cut out the dough into circles. You should get about 8-12 circles, depending on the size of your cutter.
In a medium bowl, mix together the diced peaches, sugar, flour, and cinnamon.
Place a spoonful of the peach mixture onto the center of each dough circle.
Fold the dough over the filling to form a half-moon shape. Pinch the edges together to seal the pies.
Heat about 2 inches of vegetable oil in a large, heavy-bottomed pot