Chocolate stout cake with peanut butter frosting

I've been trying to keep up with the inventory idea for the last year and it's worked out fine so far: the ingredients no longer end up in the garbage and that is great. From time to time I check the contents of my pantry/freezer/fridge to make sure nothing goes to waste and a couple of days ago I found a can of Guinness beer in the cupboard; while searching for something delicious to make with it I remembered this great cake I made months ago but still hadn't shared with you - it's another one of Donna Hay's wonderful recipes and it was the first time I ever baked with stout beer.

Chocolate stout cake with peanut butter frosting
slightly adapted from the always gorgeous Donna Hay Magazine

Cake:
1 cup + 1 tablespoon (150g) all purpose flour
¾ teaspoon baking soda
pinch of salt
½ cup (120ml) Guinness or other stout beer
½ cup (113g/1stick) unsalted butter, chopped
1/3 cup (30g) cocoa, sifted
1 egg
1/3 cup sour cream*
½ teaspoon vanilla extract
1 cup + 2 tablespoons (224g) granulated sugar

Peanut butter frosting:
½ cup (70g) icing sugar, sifted
½ cup smooth peanut butter
3 tablespoons (42g) unsalted butter, softened
½ teaspoon pure vanilla extract
2 ½ tablespoons heavy cream

Preheat oven to 180°C/350°F. Lightly butter a 1.5l loaf pan, line it baking paper and butter the paper as well.
Cake: in a medium bowl, sift together the flour, baking soda and salt. Set aside.
Place the stout and butter in a small saucepan over medium heat and stir to melt the butter. Remove from heat and whisk in cocoa; set aside.
Whisk together the egg, sour cream and vanilla. Add to the stout mixture, followed by the sugar and the sifted ingredients. Whisk to combine. Pour the batter into the prepared pan. Bake for 55-65 minutes or until a tester inserted into the center of the cake comes out clean.
Cool the cake in the pan over a wire rack for 20 minutes. Carefully unmold cake and transfer to the rack. Cool completely.

Frosting: place the sugar, peanut butter, butter and vanilla in the bowl of an electric mixer and beat until light and fluffy. Add the cream and beat for a further 2 minutes. Spread the frosting over the cooled cake to serve.

* homemade sour cream: to make 1 cup of sour cream, mix 1 cup (240ml) heavy cream with 2-3 teaspoons lemon juice in a bowl. Whisk until it starts to thicken. Cover with plastic wrap and leave at room temperature for 1 hour or until thicker (I usually leave mine on the counter overnight – except on very warm nights – and it turns out thick and silky in the following morning; refrigerate for a creamier texture)

Serves 6-8