1. Preheat oven to 350°. Whisk together first 3 ingredients in a saucepan until blended. Add peaches, tossing to coat. Cook, stirring constantly, over medium heat until thick and bubbly. Remove from heat and cool 15 minutes.
2. Meanwhile, unroll piecrusts onto a lightly floured surface; roll out each to a 12-inch circle. Fit 1 piecrust into a 9-inch pie plate. Spoon cooled peach filling into prepared crust. Place remaining piecrust over filling; fold edges under, sealing to bottom crust, and crimp. Cut 4 or 5 slits in top of pie for steam to escape.
3. Bake at 350° for 1 hour. Remove to a wire rack. Cool 2 hours before serving.