Cook first 3 ingredients in a Dutch oven over medium heat, stirring often, 35 minutes or until thickened. Remove from heat, and discard lemon. Add butter and vanilla; cool.
Fit 1 piecrust into a 9-inch pieplate according to package directions. Pour applesauce mixture into crust.
Roll remaining piecrust to press out fold lines, and cut into 1/2-inch strips. Arrange strips in a lattice design over filling; fold edges under, and crimp.
Bake on lowest oven rack at 425° for 30 to 35 minutes or until golden, shielding pie with aluminum foil to prevent excessive browning, if necessary. Serve with whipped cream, if desired.
Find recipes with ingredients that you have on hand.