Preheat the oven to 180 C (fan oven 160 C, 350 F, gas 4). Grease and line 3 x 15cm (6 inch) round cake tins.

Put the margarine in a mixing bowl with the caster sugar, eggs and milk. Sift the flour and Baking Powder on top and using an electric whisk on a low speed, gently blend the ingredients together. Increase the mixer speed and whisk for a few more seconds until thick and well mixed.

Divide the mixture equally between 3 bowls. Put aside 10g (2 tsp) Cocoa Powder for the icing, then sift the remainder on to one portion of cake batter and mix in well. Spoon into one of the prepared tins and smooth the top.

Mix the Vanilla Extract into another batch of mixture and spoon into another of the tins. Smooth the top.

Add 25 drops Pink Gel Food Colour to the remaining mixture and mix well. Spoon into the remaining tin and smooth the top.

Bake the cakes for about 30 minutes, until risen, lightly golden and firm to the touch. Cool for 5 minutes then turn on to a wire rack to cool completely. Using a serrated knife, trim away the cake tops to make them flat and carefully slice each cake in half.

To decorate, put 300g butter in a large bowl and beat until smooth. Gradually sieve and mix in the icing sugar to make a smooth buttercream, then mix in the milk to make a more spreadable consistency. Transfer 150g (5oz) to another bowl, add the reserved Cocoa Powder, and mix until well combined.

Put the remaining buttercream into another bowl and add a few drops Pink Gel Food Colour to make a pretty pastel shade. Mix the Vanilla Extract into the remaining icing.

Place one half of the chocolate cake on a serving board or plate and spread over half the chocolate buttercream. Sandwich together with the chocolate half and spread the remaining chocolate icing on top.

Place a plain cake half on top and spread with 75g (3oz) Vanilla buttercream. Sandwich together with the other half and spread the same amount of icing on top.

Repeat the layering with the pink cake, using all of the pink buttercream to sandwich them together. Gently press down on top of the whole cake to make sure it is secure.

Using about half of the remaining vanilla icing, spread it thickly round the side of the cake, then smooth it with a palette knife – warm the blade of the knife flat and run it flat against the cake to achieve a smooth effect. Spread some of the remaining icing smoothly on top of the cake to cover it completely, and neaten the top edge to make sure it is smooth and flat. Press Chocolate Hearts around the bottom edge of the cake.

Break up the Dark Chocolate and place in a heatproof bowl with the remaining butter and 10ml (2tsp) water. Place the bowl over a saucepan of barely simmering water until melted. Remove from the water and leave to cool for about 10 minutes until starting to thicken a little.

Using a teaspoon, slowly working your way round the top of the cake, spoon a little of the chocolate icing at a time on to the top edge of the cake, using a slight zig-zag motion, allowing it to drip down the sides – the drips will come to their own natural halt.

Spoon the remaining chocolate icing into the centre of the cake and carefully spread it over the top to meet the dripping edges. Leave for a few minutes in a cool place, to set.

Transfer the remaining vanilla buttercream into a piping bag fitted with a large closed star nozzle and pipe swirls in the centre of the cake. Gently press the wafers and flakes into the top of the cake. Your cake is now ready to present as a gift.