CUSTARD FILLING FOR CHOCOLATE CAKE RECIPES

Steps:

• Heat milk in microwave-safe glass or ceramic bowl in the microwave on high until hot but not boiling, 2 to 4 minutes. Combine sugar, flour, and salt together in a separate microwave-safe glass or ceramic bowl. Whisk hot milk into the sugar mixture gradually. Cook milk mixture in microwave on high in 1-minute intervals, stirring after each interval, until thickened, 4 to 5 minutes.
• Whisk eggs in a separate small bowl until pale and frothy. Whisk 1/3 cup of the milk mixture into eggs gradually, then whisk egg mixture into remaining milk mixture gradually until smooth custard forms. Heat custard in microwave on high until thickened, about 2 minutes more. Cool slightly; stir in vanilla extract. Chill custard in refrigerator until completely cooled, about 30 minutes.

Steps:

• Preheat oven to 325 degrees F. Line an 8-inch square baking dish with parchment paper.
• In a medium bowl, beat egg whites until stiff; set aside. In a large bowl, beat egg yolks, granulated sugar, butter, and vanilla until creamy. Gradually add flour and cocoa and beat until thoroughly mixed. Add milk and mix well. Gently fold in egg whites until thoroughly blended. Pour batter into baking dish.
• Bake 55 to 60 minutes, or until toothpick inserted in center comes out dry. Let cool, then refrigerate at least 6 hours. Sprinkle with confectioners' sugar before serving.