Prepare the Cake Tins: Grease three 20 cm (8-inch) cake tins and line their bases with baking paper. If using loose-bottomed tins, place them on baking trays to catch any batter that may leak. Preheat the oven to 180°C (350°F).
Melt the Butter: Place the butter in a small saucepan and melt it gently over low heat. Once just melted, pour it into a large mixing bowl.
Mix the Cake Batter: Add the oil, cocoa powder, malted milk powder, sugar, eggs, and full-fat yogurt to the melted butter. Stir until the ingredients are thoroughly combined.
Add the Hot Liquid: Pour in the just-boiled water or hot coffee. Mix quickly and carefully until the chocolate mixture is smooth.
Incorporate the Dry Ingredients: Add the flour, baking powder, bicarbonate of soda, and salt. Gently whisk until the flour is just incorporated, taking care not to overmix.
Fill the Cake Tins: Divide the batter evenly among the three prepared tins, distributing it as evenly as possible.
Bake the Cake Layers: Bake at 180°C (350°F) for 35–45 minutes. Check the centre of each cake with a toothpick; it should come out mostly clean, although a few crumbs are fine. The cake should also spring back when gently pressed.
Cool the Cakes: Leave the cakes in their tins for a few minutes after baking. Carefully run a knife around the edges to loosen them, then allow them to cool completely before removing them from the tins.
Level the Layers: Once cooled, use a serrated knife to trim any domed tops so the cake layers can stack evenly.
Assemble the Cake: Place the first cake layer on a serving plate or cake stand. Spread chocolate malt pudding-style frosting over the top, add the second layer, and repeat until all three layers are stacked with frosting between them.
Frost the Cake: Spread the remaining frosting over the top and sides of the assembled cake, covering the layers evenly.
Decorate the Cake: Sprinkle the crushed Maltesers over the frosted cake. Serve once the cake is assembled and decorated.
