01 -
Preheat oven to 320°F (fan) or 350°F (conventional). Grease and line the base and sides of a 9-inch round cake pan with baking paper.
02 -
Stir together caster sugar, self-rising flour, and cocoa powder in a large mixing bowl.
03 -
Add vegetable oil, whole milk, and beaten eggs to the dry mixture. Mix thoroughly until smooth and well combined.
04 -
Finely grate orange zest into the batter, then halve the orange and squeeze in the juice. Mix gently to combine.
05 -
Pour the batter into the prepared cake pan and bake for 45-50 minutes until risen and springy to the touch. Let cool in the tin for 20 minutes, then turn out onto a wire rack to cool completely.
06 -
Melt chopped Dairy Milk chocolate orange in a microwave-safe bowl for 60 seconds or until smooth, stirring well. Allow to cool.
07 -
Beat the salted butter until light and fluffy. Sift in icing sugar and continue beating until creamy.
08 -
Fold the cooled melted chocolate into the butter mixture. Add cocoa powder and boiling water, folding until creamy and glossy.
09 -
Spread the chocolate orange buttercream evenly over the cooled cake using a palette knife for a smooth finish.
10 -
Arrange chocolate orange buttons in a circle at the center of the cake. Attach red Smarties on each with buttercream, place edible eyes above, and position broken pretzel pieces as antlers.