chocolate peanut butter layer cake

as i've said before, i love layer cakes, but rarely make them since there's only two of us in the house. and since jason isn't a huge fan of sweets anyway, i am the one who eats the majority of the cakes around here. and it's really not good to eat a piece of a two or three layer cake a day. for a week. so last year i smartened up and bought a set of three six inch pans. they're the perfect size to serve four to six people. and it's simple to convert your favorite cake recipe into a mini version of itself, since half of a standard cake recipe perfectly fits into two six inch pans.

this year for my dad's birthday i made a petite version of one of our favorite combinations: my favorite chocolate cake layered with thick peanut butter filling and covered in ganache. 

it was the perfect size for the four of us to have a piece after dinner and me and my mom to have another the next day. 

chocolate peanut butter layer cake
cake adapted from ina garten, via my baking addiction; peanut butter filling adapted from amandeleine
makes one, three layer six inch cake

if you want to make a three layer eight or nine inch cake, double the cake ingredients and bake for about 30 minutes. also double the peanut butter filling.

for the cake:
3/4 cup + 2 tablespoons all purpose flour
1 cup sugar
6 tablespoons cocoa powder
1 teaspoon baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
1/2 cup buttermilk
1/4 cup vegetable oil
1 egg
1 teaspoon vanilla extract
1/2 cup brewed hot coffee

for the peanut butter filling:
1 cup + 2 tablespoons creamy peanut butter
1/4 cup + 2 tablespoons (6 tablespoons) unsalted butter, soft
1/2 teaspoon vanilla extract
1 cup + 2 tablespoons powdered sugar

for the ganache:
1/2 cup heavy cream
1 cup semi-sweet chocolate

1. preheat your oven to 350F and line the bottom of three six inch cake pans with parchment paper. spray the parchment and sides of the pan with nonstick spray or grease with butter and set aside.
2. in a large bowl, mix the flour, sugar, cocoa, baking soda, baking powder, and salt. set aside.
3. in a separate medium bowl, mix the buttermilk, oil, eggs, and vanilla. slowly add the wet ingredients to the dry ingredients until incorporated. slowly mix in the hot coffee. the batter will be very very thin.
4. distribute the batter between the pans. bake for about 25 minutes, or until a toothpick comes out clean. cool in the pan for about 10 minutes before removing. cool completely before filling.
5. while the cakes are cooling, make the peanut butter filling. combine all of the ingredients in a bowl and use an electric mixer to mix well. the mixture will be very thick.
6. when the cakes are cool, spread about one third of a cup of the peanut butter filling between each layer. spread a very thin layer of filling on the top cake layer and the sides of the cake. refrigerate for about 15 minutes, or until the peanut butter filling is set. spread the remainder of the peanut butter filling on the sides of the cake. don't worry so much what the top looks like since you're going to cover it in ganache.
7. to make the ganache, bring the heavy cream to a simmer in a small saucepan. place the chocolate in a medium heat proof bowl and pour the hot cream over it. let sit for a minute or two before mixing. mix until smooth.
8. slowly pour the hot ganache over the middle of the top of the cake, letting it naturally spread out to the sides or use an offset spatula to guide the ganache where you want it. let the ganache set before cutting and serving. 

2012.08.06 this is sweet as sugar cookies' pick for the secret recipe club!