5 oz. bittersweet chocolate, finely chopped
1/3 cup plus 2 Tbs. creamy peanut butter
1 Tbs. heavy cream
1 Tbs. unsalted butter2
whole eggs plus 1 egg yolk
1/4 cup sugar
1 tsp. vanilla extract
1/8 tsp. salt
1 Tbs. all-purpose flour
Whipped cream or vanilla ice cream for serving
Preheat an oven to 190°c.
To make the ganache, in a small, heatproof bowl, combine 1 oz. of the chocolate and the 1/3 cup peanut butter. Set the bowl over but not touching simmering water in a saucepan and melt the chocolate, stirring occasionally. Remove the bowl from the heat (reserve the pan of simmering water), add the cream and stir until smooth. Cover the bowl with plastic wrap and refrigerate the ganache until firm, about 20 minutes. In another small, heatproof bowl, combine the remaining 4 oz. chocolate, the 2 Tbs. peanut butter and the butter. Set the bowl over but not touching the simmering water and melt the chocolate, stirring occasionally. Remove the bowl from the heat and let cool for at least 10 minutes. In the bowl of an electric mixer fitted with the whisk attachment, combine the whole eggs, egg yolk, sugar, vanilla and salt. Beat on high speed until the mixture has nearly tripled in volume and ribbons fall from the whisk, about 5 minutes.
Remove the bowl from the mixer. Sift the flour over the egg mixture and gently fold together until just blended. Add the chocolate mixture and gently fold together until smooth and blended. Divide the batter amongnst the cupcake liners. Remove the ganache from the refrigerator and form into 8 teaspoon-size balls. Place 1 ball on top of the batter in each cake and press gently down into the batter. Bake until the cakes and the tops are set, 9 to 11 minutes. Transfer to a wire rack and let cool for 5 minutes.
