Ingredients

• 4 large eggs
• 2 cups sugar
• 1 teaspoon vanilla
• 1 cup milk
• 2 tablespoons unsalted butter
• 2 cups all-purpose flour
• 1 teaspoon baking powder
• a 12-ounce jar creamy or chunky peanut butter (about 1 1/3 cups)
• 1 pound milk chocolate, chopped

Instructions

1. Preheat oven to 350° F. Butter and flour a 17 1/4- by 11 1/2- by 1-inch jelly-roll pan, knocking out excess flour.
2. In a bowl with an electric mixer beat eggs with sugar and vanilla until mixture is very thick, pale, and forms a ribbon when beaters are lifted, about 3 minutes. In a small saucepan bring milk and butter just to a boil. Cover pan and remove from heat. Sift flour and baking powder into egg mixture and beat just until combined. With mixer running add hot milk mixture in a stream and beat just until combined. Spread batter evenly in pan and bake in middle of oven 20 to 25 minutes, or until golden and springs back when touched lightly. Cool cake in pan on a rack.
3. Make topping: In a small saucepan heat peanut butter over low heat, stirring, just until barely warm and thin enough to spread easily. Spread peanut butter evenly over cake and chill, uncovered, 30 minutes, or until peanut butter is firm. In a double boiler or metal bowl set over a saucepan of barely simmering water melt chocolate, stirring, and cool to room temperature.
4. In a small saucepan heat peanut butter over low heat, stirring, just until barely warm and thin enough to spread easily. Spread peanut butter evenly over cake and chill, uncovered, 30 minutes, or until peanut butter is firm. In a double boiler or metal bowl set over a saucepan of barely simmering water melt chocolate, stirring, and cool to room temperature.
5. Pour chocolate onto cake and spread evenly over peanut butter. Cut cake into 24 squares and chill in pan, uncovered, until chocolate is firm. Recut cake squares and serve chilled or at room temperature.