You will never again look at the classic peanut butter-and-jelly brown-bag sandwich without thinking of this witty (and mouthwatering) semifreddo cake. This confection features white butter cake (the "sandwich bread"), airy peanut butter mousse, and blueberry mousse made with pureed fresh fruit. Strained jam is spread on top as a glaze. Store the confection in the freezer, then display it a half hour before cutting so it can warm up, suggests contributing editor and pastry chef Jason Schreiber. Then serve this version of PB&Js in 1-by-2-inch slices. "You don't need a big piece," Schreiber adds. "It's a very rich cake."



White Butter Cake
Peanut Butter Mousse
Blueberry Mousse


Instructions Checklist
  • White butter cake: Preheat the oven to 350 degrees. Brush two 9-inch square cake pans with butter. Line pans with parchment paper. Butter parchment and dust with flour, tapping out any excess. Set aside.

  • Whisk together flour, baking powder, and salt in large bowl; set aside. In another bowl, stir milk and vanilla to combine; set aside. Beat butter in a mixer bowl until pale and fluffy, about 3 minutes. Add 3 cups sugar in a steady stream; mix until pale and fluffy, about 3 minutes.

  • Reduce speed to low. Add flour mixture in 3 additions, alternating with milk mixture, and beginning and ending with flour; mix just until combined.

  • In clean mixing bowl, whisk egg whites with remaining 1/2 cup sugar just until stiff peaks form. Stir 1/3 of the egg whites into batter to lighten. Gently fold in remaining whites in 2 batches. Divide batter among prepared pans; smooth tops with an offset spatula. Firmly tap pans on a work surface to release any air bubbles.

  • Bake until a cake tester inserted into the centers comes out clean and the tops are springy to the touch, 30 to 45 minutes. Let cool in pans on wire racks for 15 minutes. Invert cakes onto racks. Remove parchment; reinvert and cool completely.

  • Peanut butter mousse: In a microwave-safe bowl, sprinkle gelatin over 2 teaspoons cold water; set aside. Place heavy cream into bowl of electric mixer fitted with a whisk attachment; beat on medium-high speed until soft peaks form, about 3 1/2 minutes. Transfer whipped cream to a bowl; refrigerate 1 hour.

  • In a clean bowl, beat egg yolks with whisk on high speed until pale and frothy, 4 to 5 minutes. Meanwhile, in a small, heavy saucepan, bring sugar, corn syrup, and 3 tablespoons water to a rolling boil over high heat. Cook until clear, large bubbles form, about 1 minute, or until it reaches 238 degrees on a candy thermometer (soft-ball stage). Reduce mixer speed to medium-low. Carefully pour hot syrup down side of bowl. Raise speed to medium-high. Mix until slightly thickened, about 5 minutes. Melt the gelatin in the microwave for 20 seconds on high power. Whisk in peanut butter in three additions, followed by the gelatin, vanilla, and a pinch of salt.

  • Add 1/3 of whipped cream to the peanut butter mix. Fold in remaining whipped cream in 3 batches. Stir until combined.

  • Blueberry mousse: Place lemon juice in small bowl and sprinkle with gelatin; set aside. In a blender, puree blueberries until smooth, scraping down sides of bowl as needed. Pour through a fine-mesh sieve into a measuring cup, pressing on solids (you should have about 2 1/2 cups puree); discard solids.

  • In medium saucepan, combine puree and sugar over medium heat. Cook until reduced by half; remove from heat. Add gelatin mixture and cook, stirring constantly, just until gelatin dissolves, about 1 minute. Transfer mixture to medium bowl and let cool to room temperature, 1 hour, stirring occasionally. In large bowl, using electric mixer, beat cream on medium-high until firm peaks form, about 2 minutes. With a rubber spatula, gently fold in puree mixture until combined.

  • Assemble the semifreddo: Trim the 2 white butter cakes level; cut each cake horizontally into 3 even 1/2-inch layers. (Set aside 2 layers for later use. Extra layers can be stored, wrapped and frozen, for up to 1 month.) Trim each cake layer to 8-inch square. Place 1 cake layer in bottom of an 8-inch-square mold with 4-inch-tall sides.

  • Transfer peanut butter mousse into a pastry bag fitted with a 1/2-inch round tip. Pipe 1/2-inch layer of peanut butter mousse on top of cake. Top mousse with cake layer.

  • Transfer blueberry mousse into pastry bag fitted with 1/2-inch round tip. Pipe 1/2-inch layer of blueberry mousse on top of cake.

  • Repeat the process until you have 8 total layers, 4 of cake alternated with 4 of mousse (the final layer will be blueberry mousse). Freeze cake for 3 hours.

  • Spread a thin layer of blueberry jam on top of semifreddo and return to freezer for 12 hours.

  • Remove square mold either by warming outside of cake with a heat gun (recommended) or allowing the cake to warm slightly on its own (which will result in a messier exterior). Freeze for at least 1 hour or up to 3 days. Before serving, let cake warm at room temperature for 30 minutes.