Boston Cream Pie

In a medium microwave bowl, combine sugar, flour, egg and ¼ c. milk together. Heat, uncovered, in microwave oven 2 minutes or until sauce is thickened and smooth. Stir every 30 seconds. Place in refrigerator to chill. In a 1 quart measuring cup, combine corn syrup, chocolate chips and butter. Microwave, uncovered, for 2½-3 minutes or until chocolate is melted. Stir occasionally. Gradually stir in milk and vanilla. Blend well. Microwave, uncovered, 1½ minutes. Chill in refrigerator. While custard and topping are cooling, prepare cake mix according to directions. Grease 2 – 8-inch cake pans. Divide batter between each prepared cake pan. Cover each cake pan with clear plastic wrap and heat in microwave oven 6 minutes or until a toothpick inserted in the center comes out clean. Invert cakes onto a cooling rack. When cake has cooled, place one layer on a serving plate. Spread chilled custard on top. Place other layer on top of custard and spread chilled chocolate sauce over top and let drizzle down sides. Chill in refrigerator for 1 hour before serving.