Southern Sweet Potato Pie

3 large sweet potatoes 2 tbsp butter
1/2 cup sugar 1/2 tsp cinnamon
1/2 tsp nutmeg 1 egg
2 egg whites 4 tsp sugar
9" baked pie shell
Boil potatoes until soft. Peel and mash real good with 2 tbsp butter. Add sugar, cinnamon, nutmeg and egg, beat well. Fill pie shell and cover with meringue made of beaten egg whites and 4 tsp sugar. Brown in medium oven.