Chocolate Guinness Cake

Grease a 23 cm, 9 inch cake tin with a removable base and line the bottom with parchment. This prevents sticking and helps the sponge release cleanly. Preheat the oven to 180°C, 350°F so the heat is steady by the time the batter is mixed.

Place a small saucepan over low heat. Add the butter and let it melt gently without bubbling. Whisk in the cocoa powder until smooth and glossy, then pour in the Guinness. The mixture will thin out and darken. Remove from the heat and let it cool for a few minutes so it does not cook the eggs later (a loose texture here is normal, it thickens once combined with the dry ingredients).

In a large mixing bowl, stir together the plain flour, baking soda and caster sugar. Use your fingers to break up any clumps. This ensures an even batter and prevents dry pockets once the wet ingredients are added.

Make a well in the dry ingredients and pour in the warm Guinness mixture. Add the eggs, sour cream and vanilla extract. Whisk slowly at first, then continue until the batter becomes thick, glossy and smooth. Small bubbles rising to the surface are normal and help the cake rise evenly.

Pour the batter into the prepared tin and smooth the surface with a spatula. Bake for about 60 minutes until a skewer inserted in the center comes out clean and the top springs back gently when pressed. If the top browns too quickly, place a loose sheet of parchment on top for the last 15 minutes. Cool completely in the tin before frosting so the topping stays firm.

Place the white chocolate in a heatproof bowl set over a small saucepan of gently simmering water. Stir until melted and smooth, then set aside for 10 minutes so it cools slightly. In a separate bowl, beat the butter and cream cheese with a hand mixer until light and creamy. Pour in the cooled white chocolate and mix again, then add the sifted icing sugar gradually until the frosting becomes thick, smooth and spreadable (if it feels soft, chill it for a short time to firm it).

Lift the cooled cake onto a serving plate or stand. Spoon the frosting on top and spread it into soft, even swirls using an offset spatula. The pale frosting against the dark sponge gives it the classic stout cake look. Slice once the frosting feels lightly set.