Imagine moist, chocolatey cake, enveloped in fluffy peanut butter-cream cheese frosting and topped with a layer of peanutty chocolate ganache. It’s like what would happen if a peanut butter cup accidentally wandered through some radioactive ooze. It’s a teenage mutant ninja peanut butter cup cake.

You can use any kind of cocoa powder. I had Ghiradelli and Hershey’s, so I used a combination of both. I think Ghiradelli is probably better, but it’s also more expensive. And it’s not like Hershey’s is bad.

I used my lazy method of sifting, as usual: Dump the ingredients you are supposed to sift together into a sieve on top of a large mixing bowl. Then stir inside the sieve to combine and coax the ingredients down into the bowl. (The salt I use is too coarse to go through the sieve, so I always sift everything else through and then turn the sieve upside down and dump whatever’s left on top)

Here’s the thing about this cake: It is really, really rich. Anyone who loves peanut butter and chocolate will adore it. But you should cut the slices very thin and serve it with a glass of milk so no one passes out.

Also: It isn’t technically difficult to make (as long as you follow the directions), and you could even do the whole thing with just a whisk if you don’t have an electric mixer. But it does take a long time. You may want to plan it out so you bake the cake part in the morning, then refrigerate or freeze the cake layers while you do something else. Then make the peanut butter cream cheese frosting and assemble the cake around lunch time, and stick it in the fridge and go do something else. Later, make the chocolate-peanut butter frosting, pour it on and put it in the fridge again. Because if you try to do the whole thing at once, it will take hours.

There are a couple of ways to cut a round of parchment (or wax) paper for a cake pan. I usually trace the bottom of the cake pan on the paper, then cut it out. You can also fold it into quarters (and then fold it twice more), lay the point of the triangle in the middle of the bottom of the upside down cake pan, and cut it along the edge of the pan. (Watch a video of this here… I watched it without sound, so I apologize if there is annoying music or something).

This cake is really soft, which is great when you eat it. It does make it kinda hard to handle though, so you should definitely freeze the layers for 15-20 minutes before you try to assemble the cake.

You have to respect a cake that has two different types of frosting. This peanut butter cream cheese frosting is the one that goes in between the layers and all over the cake. The other is basically poured on top, and it makes the cake look super professional and fancy — and you don’t need any special tools or decorating skills.

I used the peanut butter that was left over from the pb&j bars last week. Remember to avoid natural peanut butter, or the consistency of the frosting(s) might be off.

I posted more explicit instructions on how to assemble and frost a cake here, but here are a few tips: 1. If one of the cake layers is smaller than the others, put it in the middle or the top. 2. For a three layer cake, I usually put the first and second layers on with the flat side facing up and the third layer with the flat side facing down. 3. The cake will look better if you put a thin layer of frosting on the whole thing (crumbs will show through), stick it in the fridge for 10-15 minutes to set it, and then put the rest of the frosting over the first layer.

Also remember that it doesn’t really matter how the top of this looks, because you are going to pour a bunch of peanut-butter-chocolate magic on it.

If you don’t have a double boiler (I don’t), try to find a heat-proof bowl that fits into one of your pots. Then put some water in the pot and bring it almost to a boil. I put the bowl in the pot before I start heating it, because I am pretty sure the glass would shatter if I set it down in nearly boiling water.

You’ll need to stir this (not constantly, but frequently) to make sure the chocolate all melts and nothing burns. If you can’t find a bowl that fits in one of your pots, then you can microwave it — there may be instructions on the chocolate wrapper — but do it very gradually so it doesn’t burn.

You will want to have the half and half at room temperature (or close to it), and add it just a little at a time. Otherwise, the chocolate might seize and that would be extremely upsetting (though still fixable).

I promise this drippy look is not hard. The cake and frosting should be cold and the chocolate-peanut-butter mixture should be warm. Then you just pour the chocolate on top and sort of spread it with a knife or spatula so it drips over the side. That’s it.

Chocolate Peanut Butter Cake (From Smitten Kitchen)
Makes an 8-inch triple-layer cake; serves 12 to 16 (or more)
2 cups all-purpose flour
2 1/2 cups sugar
3/4 cup unsweetened cocoa powder (Dutch process, if possible)
2 teaspoons baking soda
1 teaspoon salt
1 cup vegetable oil (I use canola)
1 cup sour cream
1 1/2 cups water
2 tablespoons distilled white vinegar
1 teaspoon vanilla extract
2 eggs

Preheat the oven to 350 degrees. Butter the bottoms and sides of three 8-inch round cake pans. Line the bottom of the pans with rounds of parchment or waxed paper — then butter the paper. Set the eggs and sour cream out on the counter to come to room temperature.

Sift the flour, sugar, cocoa powder, baking soda and salt into a large bowl. Whisk to combine them well. Add the oil and sour cream and whisk (or use electric mixer) to blend. Gradually beat in the water. Blend in the vinegar and vanilla. Whisk in the eggs and beat until well blended. Scrape down the sides of the bowl and be sure the batter is well mixed (it will be very thin). Divide evenly among the 3 prepared cake pans*.

Bake for 30 to 35 minutes, or until a wooden toothpick inserted in the center comes out almost clean. Let cool in the pans for about 20 minutes. Invert onto wire racks, carefully peel off the paper liners, and let cool completely. The cakes will be really soft, so be careful. Wrap them up in plastic and stick them in the freezer for about 30 minutes to firm them enough to handle.

To frost the cake, place one layer, flat side up, on a cake stand or large serving plate. Spread about 2/3 cup of the Peanut Butter Frosting evenly over the top. Repeat with the next layer. Place the last layer on top (flat side down) and frost the top and sides of the cake with a thin layer of frosting. Stick the cake in the fridge for 15 to 30 minutes, then use the rest of the frosting to smoothly cover the cake. Then put the cake in the fridge again before adding the chocolate-peanut butter glaze.

Once the cake is cool, but when the chocolate-peanut butter glaze is still warm, pour the glaze over the top of the cake. Use a butter knife or spatula to spread it evenly over the top and to the edges so some drips down the sides. Refrigerate for at least 30 minutes to allow the cake to set. Remove from the fridge about an hour before serving.

*This is a great time to use a food scale, if you have one. Otherwise, you can eyeball it or measure the batter and pour equal amounts into each pan.

Peanut Butter Frosting
10 ounces cream cheese, at room temperature
1 stick (4 ounces) unsalted butter, at room temperature
5 cups powdered sugar
2/3 cup smooth peanut butter, not the “natural” kind

In a large bowl, beat the cream cheese and butter with an electric mixer until light and fluffy. Add the powdered sugar 1 cup at a time, mixing thoroughly after each addition and scraping down the sides of the bowl frequently. Continue to beat on medium speed until light and fluffy, 3 to 4 minutes. Then add the peanut butter and beat until thoroughly blended.

Chocolate-Peanut Butter Glaze
8 ounces semi-sweet chocolate, coarsely chopped
3 tablespoons smooth peanut butter
2 tablespoons light corn syrup
1/2 cup half-and-half

Set the half-and-half on the counter to come to room temperature.

In the top of a double boiler — or in a bowl set over simmering water — combine the chocolate, peanut butter and corn syrup. Cook, stirring often, until the chocolate is melted and the mixture is smooth.
Remove from the heat and whisk in the half-and-half, beating until smooth. Use while still warm.