3 tablespoons butter
1/2 cup all-purpose flour
1/3 cup dark brown sugar
1/2 cup chopped pecans
Preheat oven to 350 degrees F (175 degrees C). In a large bowl, combine pumpkin, apple butter, 1/4 cup brown sugar, cinnamon, nutmeg, and salt. Stir in eggs and evaporated milk. Pour into prepared pie shell. Bake in preheated oven for 50 to 60 minutes, or until a knife inserted 2 inches from the center comes out clean. Sprinkle streusel topping over the pie, and bake for an additional 15 minutes.
To make the streusel topping: In a small bowl, combine butter, flour, and 1/3 cup brown sugar. Stir until mixture resembles coarse crumbs. Stir in pecans.