Fluffernutter Sundae Cake

Chocolate, peanut butter, and marshmallow--can you go wrong? This is a fabulous flavor combination! The cake is easy to mix together and results in a tender, chocolatey cake. I don't have Double Dutch dark cocoa, so I used mostly dutch-processed cocoa with a little black cocoa mixed in. I had a little trouble with the marshmallow frosting. Mine REALLY deflated when I added the butter. The frosting tasted incredible, but it was pretty loose. I would recommend using a 7-minute frosting if making a layer cake. The frosting recipe here would be perfect for a 9x13 cake, though. It was very tender, stayed soft, and tasted just like fresh marshmallows.

Fluffernutter Sundae Cake

Dark Chocolate Cake

2 cups (14 ounces) sugar
2 cups (8 ½ ounces) unbleached all-purpose flour
2 tablespoons (1/2 ounce) cornstarch
¾ cup (2 ¼ ounces) Double Dutch dark cocoa, strained to remove lumps
2 teaspoons baking powder
½ teaspoon baking soda
1 teaspoon salt
4 large eggs
¾ cup (5 ¼ ounces) vegetable oil
2 teaspoons vanilla extract
1 ¼ cups (10 ounces) water

Preheat the oven to 350°F. Grease and flour a 9x13-inch pan OR line pan with parchment, and spray the parchment and the pan. Clip the paper to the sides of the pan with paper clips or spring clips to keep the paper from flopping over on the cake. (I used 2 x 9-inch round pans.)

In a medium bowl, mix together the dry ingredients. Add the eggs, oil, and vanilla; beat on medium speed for 2 minutes, then scrape the bottom and sides of the bowl. Stir in the water; the batter will be thin. Pour the batter into the prepared pan.

Bake the cake for 30 to 35 minutes, or until a cake tester inserted into the center comes out clean. Cool for 15 minutes, then turn out of the pan (if desired), remove the parchment, and allow the cake to cool completely on a rack.

Peanut Butter Filling

¾ cup (7 1/8 ounces) creamy peanut butter
1 teaspoon vanilla extract
2 cups (8 ounces) confectioners’ sugar
6 to 8 tablespoons (3 to 4 ounces) milk

Place the peanut butter in a mixing bowl with the vanilla. Stir the confectioners’ sugar through a strainer (to eliminate lumps) into the bowl, and mix at low speed until the mixture is crumbly. Add 4 tablespoons of the milk and mix at low speed. You’ll see the mixture’s texture go from crumbly to smooth, but stiff. Stop the mixer and scrape the sides and bottom of the bowl. After that, add the milk, 1 tablespoon at a time, until the filling is smooth and spreadable.

Marshmallow Icing

1 packet (2 teaspoons) unflavored gelatin
1 cup (8 ounces) water, divided
2 teaspoons vanilla extract
1 cup (7 ounces) granulated sugar
½ cup (5 ½ ounces) light corn syrup
¼ cup (1 ½ ounces) meringue powder
¼ cup (1/2 stick, 2 ounces) unsalted butter, softened

Sprinkle the gelatin over the ¼ cup of the water and add the vanilla. Set the mixture side to let the gelatin soften. In a saucepan set over low heat, stir together the sugar, light corn syrup, and ¼ cup water, cooking and stirring until all of the sugar is dissolved. Bring the mixture to a boil, cover the pan, and cook for 3 minutes, washing down any sugar crystals that may cling to the sides of the pan. Remove the pan from the heat.

While the sugar syrup is cooking, combine the meringue powder and the remaining ½ cup of cold water in a medium bowl. Beat until peaks form. Carefully add the hot sugar syrup to the beaten egg whites, then continue to beat until the mixture is stiff and glossy.

Melt the softened gelatin in a saucepan set over low heat, or in a microwave. Add ist to the beaten egg whites, and beat until the icing feels cool, about 10 minutes. Beat in the osft butter quickly. Don’t over-beat at this point; if the mixture is too warm, or you beat it too much, you’ll lose volume (though the icing will still taste good).

The icing is easy to spread and will have a smooth appearance at this point. Use it right away before it begins to set up. As the icing sets it will develop the texture of soft marshmallows.

To assemble the cake: Spread the peanut butter filling over the top of the cake (or between the layers if making a layer cake). Reserve a few tablespoons filling for decorating the top. Spread the marshmallow icing over the entire top (and sides if desired) of the cake. Quickly pipe peanut butter lines (using reserved peanut butter filling) across the cake from side to side and drag a toothpick through perpendicular to the lines for a pretty effect.

Recipe Source: King Arthur Flour's The Baking Sheet Winter 2010