HEAT oven to 425 degrees F. Combine pumpkin, sweetened condensed milk, eggs, maple flavoring, cinnamon, salt, ginger and nutmeg in large bowl. Mix well. Pour into pie crust.
BAKE 15 minutes. Reduce oven temperature to 350 degrees F. Bake an additional 30 minutes.
COMBINE brown sugar, flour and cinnamon in medium bowl. Cut in butter with pastry blender or 2 knives until mixture resembles coarse crumbs. Stir in nuts. Remove pie from oven. Top evenly with crumb mixture.
BAKE an additional 10 minutes. Cool. Garnish as desired.