In a small bowl, sift together the flour and sugar; with a pastry blender, cut in butter until mixture resembles coarse pebbles. Set aside. Prepare peaches and immediately sprinkle with lemon juice to prevent fruit from discoloring. In a second small bowl, combine brown sugar, ¼-cup flour, nutmeg, cinnamon, and salt, mixing well. Add mixture to peaches, folding gently to blend. Arrange pie crust in pie plate; turn peach mixture into crust. Dot with butter and/or sprinkle with butterscotch flavoring, if desired. Evenly sprinkle crumb topping over peach filling.
Bake in a preheated hot (400 degrees F.) for about 50 to 60 minutes, or until topping is crisp and golden brown, peaches are tender, and juice is thickened and bubbly hot. Cool pie on wire rack. Serve warm or at room temperature, plain, or topped with sweetened flavored whipped cream or other whipped topping, or vanilla ice cream as desired.
Variation: May use nectarines or pears in place of peaches, if desired.