For a one crust pie
1 ¼ cups all-purpose flour
¼ t salt
1/8 t baking powder
8 T (1 stick) cold unsalted butter
2-3 T cold water
Combine the flour, salt and baking powder in a medium-sized mixing bowl. Cut the butter into 1 Tablespoon sized pieces and toss with the dry ingredients to coat. Using your hands or a pastry blender, rub the butter into the flour and break up until the mixture resembles course-ground cornmeal. Sprinkle in 2 Tablespoons cold water and stir with a fork until the dough begins to hold together. If it is too dry add a little bit more water at a time, until the dough holds together easily.
Turn the dough out onto a lightly floured surface and form it into a disk. Sandwich the disk between two pieces of plastic wrap and press into a 6 inch circle. Refrigerate until firm, at least an hour.