Cook first 3 ingredients in a Dutch oven over medium heat, stirring often, 35 minutes or until thickened. Remove from heat. Discard lemon. Add butter and vanilla. Cool.
Fit 1 piecrust into a 9-inch pieplate according to package directions. Pour in applesauce mixture.
Roll remaining piecrust to press out fold lines; cut into 1/2-inch strips. Reserve 4 strips. Arrange remaining strips in a lattice design over filling; fold edges under, and crimp.
Cut reserved pastry strips in half lengthwise. Lay halves side by side, and twist; arrange around inner edge of pie.
Bake on lowest oven rack at 425° for 30 to 35 minutes or until golden, shielding with aluminum foil to prevent excessive browning, if necessary. Serve with Spiced Ice Cream.
