From King Arthur's Flour. They suggest baking in either a 9 x 13 inch pan, two 9 inch pans, or three 8 inch pans, and they also suggested a variety of frostings. The most appealing option to me is to bake in two 9 inch pans and then split each layer horizontally for a total of four layers. Then, using their recipes, have fillings of caramel fudge and chocolate frosting with chocolate frosting around the outside. I'm including the recipes for those frostings below. I'm not always a fan of just peanut-butter flavored desserts but the comination of chocolate and peanut butter works for me. .
Ingredients
8 tablespoons (113g) unsalted butter, softened
2 cups (426g) light brown sugar or dark brown sugar, packed
1 tablespoon King Arthur Pure Vanilla Extract
1 tablespoon baking powder
1/2 teaspoon salt
5 large eggs, at room temperature
2 cups (240g) King Arthur Unbleached All-Purpose Flour
1 cup (227g) milk, at room temperature
Instructions
1. Preheat the oven to 350°F. Choose your pan(s); this recipe will fit two 9" round cake pans, three 8" round cake pans, or a 9" x 13" pan. Grease the pan(s) or line with parchment.
2. In the bowl of a stand mixer fitted with the flat beater attachment or working in a large bowl with a handheld electric mixer, combine the peanut butter, butter, and brown sugar. Mix until smooth. Scrape down the sides of the bowl and add the vanilla, baking powder, and salt. Beat in 2 of the eggs, then about 1/4 cup (30g) of the flour (this will keep the batter from curdling).
3. Beat in the 3 remaining eggs one at a time. Scrape the bowl again and add 1/3 of the remaining flour to the batter, beating gently to combine. Gently beat in half the milk. Mix in half of the remaining flour, then the remaining milk. Stir in the remaining flour. Scrape the bowl once more, and beat for another 30 seconds.
4. Divide the batter between the prepared pan(s) and level the top. (The total weight of the batter is about 1530g, if you’re weighing the batter evenly into your pans.)
5. Bake the peanut butter cake(s) for 33 to 35 minutes for 9" layers, 30 to 33 minutes for 8" layers, or 45 minutes for a 9" x 13" cake, until the top springs back when lightly pressed in the center and the edges just begin to pull away from the sides of the pan.
6. Remove the peanut butter cake(s) from the oven and cool in the pans on a rack for 20 minutes. Then turn the cakes out of the pans and return them to the rack to cool completely before frosting.
This is from a King Arthur's Flour recipe for an over the top cake, but they also suggested it as a filling for the peanut butter cake above. The other cake was four layers as well, so it would be right for this cake if the two layers baked in the 9-inch pans were split. The other cake also had a layer of frosting on top of the caramel fudge layers, vanilla, in that recipe but I would use chocolate, so between each cake layer there'd be a layer of caramel fudge filling and a layer of chocolate frosting. Plus of course the chocolate frosting around the outside of the cake. I don't have a problem with any of this.
Ingredients
2 1/4 cups (479g) light brown sugar, packed
1 tablespoon + 1 1/2 teaspoons (30g) light corn syrup or dark corn syrup
12 tablespoons (170g) unsalted butter
1/2 teaspoon salt
3/4 cup (170g) heavy cream or whipping cream
1 1/2 teaspoons King Arthur Pure Vanilla Extract
Instructions
1. Before you begin, split the two cake layers horizontally into two layers each so you have four layers, and place one of them on a cake serving platter.
2. Place all the ingredients except the vanilla in a 2-quart saucepan. Cook over medium heat, stirring occasionally, until the sugar melts.
3. Once the mixture comes to a boil, don’t stir. Cook until it reaches 238°F on a digital thermometer.
4. Remove the filling from the heat, and add the vanilla. Let the filling sit in the saucepan without stirring for about 8 minutes, to cool just a bit.
5. Stir the still-warm filling with a sturdy spoon until it leaves lines on the bottom of the pan and begins to thicken. As soon as that happens, immediately pour it over the cake layer on the serving plate, plus two of the remaining three layers (about a 1/4 cup each layer). You have about 30 seconds before the filling starts to set. Use up all the frosting, it’s OK if it runs over the edges a bit.
Also from King Arthur's Flour, another frosting they recommended for the peanut butter cake. I would spread this on top of the caramel fudge filling described just above, and then over the outside of the cake. That's a lot of chocolate. I don't have a problem with this. .
Ingredients
1 3/4 cups (149g) unsweetened cocoa, Dutch-process or natural
3 1/2 cups (397g) confectioners' sugar, divided
1 teaspoon espresso powder, optional, for enhanced chocolate flavor
1 cup (227g) heavy cream, at room temperature
16 tablespoons (227g) unsalted butter, softened
1/8 teaspoon salt
2 teaspoons King Arthur Pure Vanilla Extract
Instructions
1. Sift or sieve the cocoa, 1 1/2 cups (170g) confectioners' sugar and espresso powder into a bowl.
2. Bring the cream to a simmer on the stove or in the microwave, and whisk into the cocoa mixture. At first the mixture will look grainy; continue whisking for a minute. You'll see the lumps disappear as the sugar dissolves and the cocoa hydrates. Set aside to cool to room temperature.
3. Place the butter, salt, and 2 cups (227g) sifted or sieved confectioners' sugar in a large mixing bowl and beat until the mixture is smooth and fluffy. Beat in the vanilla.
4. With the mixer running on low speed, add the cocoa mixture a spoonful at a time until it's all incorporated. Scrape the bowl, then beat at medium speed for one minute more. Use to frost cake as needed.
5. Store frosting in an airtight container in the refrigerator for up to 5 days, or freeze for up to 6 months. Bring to cool room temperature before spreading or piping.