Active Time

　　45 min

　　Total Time

　　1 hr

　　These cakes are actually better made ahead. They become richer and fudgier one to two days after baking.

　　

Ingredients

Makes 18 cakes

　　

For peanut butter mixture

3/4 cup cream cheese (6 oz), softened

　　1 1/4 cups chunky peanut butter (12 oz)

　　6 large egg yolks

　　2/3 cup granulated sugar

　　1/4 cup all-purpose flour

　　

For chocolate mixture

1 1/4 cups unsweetened cocoa powder (not Dutch-process)

　　1 1/4 cups boiling water

　　3 1/2 oz fine-quality bittersweet chocolate (not unsweetened), finely chopped

　　1 (8-oz) container sour cream

　　1 tablespoon vanilla

　　2 cups all-purpose flour

　　1 3/4 teaspoons baking soda

　　3/4 teaspoon salt

　　2 1/2 sticks (1 1/4 cups) unsalted butter, softened

　　2 cups packed light brown sugar

　　3 large eggs

　　Accompaniment: vanilla ice cream or whipped cream

　　

Special Equipment

2 large pastry bags with 3/4-inch openings (or large heavy-duty sealable plastic bags with 1 corner snipped off) and 3 mini angel-food-cake pans (each with molds for six 6- by 3 1/2- by 1 3/4-inch cakes) or large-muffin pans (1 cup)

　　

Step 1

Preheat oven to 350°F.

　　

Make peanut butter mixture:

Step 2

Beat together cream cheese and peanut butter in a bowl with an electric mixer until smooth. Add yolks, sugar, and flour and beat until just combined. Transfer to a pastry bag and chill.

　　

Make chocolate mixture:

Step 3

Put cocoa powder in a bowl and add boiling water in a stream, whisking until smooth. Stir in chopped chocolate and let stand 1 minute, then whisk until smooth. Cool to room temperature, then whisk in sour cream and vanilla.

　　

Step 4

Whisk together flour, baking soda, and salt. Beat together butter and brown sugar in a large bowl with cleaned beaters until pale and fluffy, then add eggs 1 at a time, beating after each addition until just combined. Reduce speed to low and add flour mixture and cocoa mixture alternately in 3 batches, beginning and ending with flour mixture and beating until batter is just combined.

　　

Fill baking pans:

Step 5

Spoon some of chocolate mixture into second pastry bag and pipe into well-buttered cake molds to fill each about one fourth of the way. Refill pastry bag as needed.

　　

Step 6

Form 3 evenly spaced, equal pockets of peanut butter mixture in each cake by placing tip of pastry bag with peanut butter mixture onto bottom of mold and squeezing about a heaping teaspoon each time.

　　

Step 7

Fill molds three-fourths full with remaining chocolate mixture, smoothing tops but being careful not to disturb peanut butter mixture.

　　

Step 8

Bake cakes in upper and lower thirds of oven, switching position of pans halfway through baking, until a tester comes out with crumbs adhering, 15 to 18 minutes (cakes will be dark).

　　

Step 9

Run a thin knife around inside edges of molds and gently invert cakes onto racks, then cool completely.

　　Cooks' notes:

　　• Chocolate and peanut butter mixtures can be spooned, instead of piped, into molds; don’t worry if the peanut butter dollops are not perfectly uniform in size.

　　• Cakes may be made 2 days ahead and kept in 1 layer in an airtight container at room temperature.