Skillet Chocolate Pie
["3 egg yolks", "3 Tbsp. plain flour", "1 1/2 c. milk", "1 tsp. vanilla", "1 c. sugar", "3 Tbsp. cocoa", "3 Tbsp. butter"]
["Mix milk and egg yolks in a heavy iron skillet.", "Sift flour, cocoa and sugar.", "Cook over low heat until thick.", "Add butter and vanilla.", "Put in a baked 9-inch pie shell."]
["egg yolks", "flour", "milk", "vanilla", "sugar", "cocoa", "butter"]