– 200g salted butter, softened, plus extra for the tin – 200g golden caster sugar – 1 tsp vanilla extract – 3 eggs, beaten – 100g soured cream – 3 tbsp cocoa powder
– 200g plain flour – 1 tsp baking powder – ½ tsp bicarbonate of soda – 1 tbsp Horlicks powder – Maltesers and mini chocolate eggs, roughly chopped, to decorate
– 200g milk chocolate, finely chopped – 250ml double cream – 2 tbsp Horlicks powder
Make ganache first. Put chopped chocolate in a heatproof basin. Whisk the double cream and Horlicks powder in a small skillet over low heat until steaming. Overtop the chocolate.
Wait 3 minutes for the chocolate to melt, then whisk until you have a silky ganache. Chill covered for 1-2 hours.
Preheat the oven to 180C/160C fan/gas 4. Butter and paper a 33cm x 22.5cm x 5cm traybake tin.
In a large bowl, mix butter and golden caster sugar with an electric whisk until pale, light, and fluffy. Add vanilla, eggs, and soured cream and beat again until smooth.
Sift cocoa, flour, baking, bicarb, and Horlicks. Fold until smooth and flour-free. Scrape and smooth the tin.
Bake until a skewer inserted in the middle comes out clean, 25 minutes. Cool in the tin for 10 minutes, then gently invert onto a wire rack to finish cooling.
Cool the cake and ganache, then whip the ganache with an electric whisk until it has a gentle peak. Don't overwhip.
Use a palette knife to spread the whipped ganache over the cake, then sprinkle with chopped Maltesers and chocolate eggs. Cut into pieces to serve.