3/4 cup sugar
3 tsp all-purpose flour
1 tsp freshly grated nutmeg
1/8 tsp salt
1 large egg
1 1/2 c sour cream
1 tsb unsalted butter, melted
1 tsp vanilla extract
1 prebaked 9-inch pie shell
Preheat oven to 400°. Sift sugar, flour, nutmeg, and salt together onto a piece of waxed paper. In a large bowl, whisk the egg with the sour cream. Add dry ingredients to the egg mixture and mix well. Add the melted butter and vanilla, and whisk until smooth. Pour filling into prebaked pie shell, and place the pie on a baking sheet. Bake the pie in the bottom third of the oven for 10 minutes, then reduce the heat to 300°. and continue baking until the filling is set, about 20 to 25 minutes. Remove the pie from the oven and let it cool to room temperature on a wire rack. Serve immediately, or refrigerate and serve the next day. 
