Chocolate Pie
["1/2 c. sugar", "1/4 c. flour", "2 Tbsp. cocoa", "2 egg yolks*", "1 tsp. vanilla", "2 c. milk", "1 (8 or 9-inch) pie shell"]
["*Keep egg whites for meringue."]
["sugar", "flour", "cocoa", "egg yolks", "vanilla", "milk", "pie shell"]