Method

1. Preheat the oven to 180C/160C Fan/Gas 4. Grease and line the bases of four 20cm/8in cake tins with baking paper.

2. In a freestanding mixer or a large bowl, cream the sugar and baking spread together until pale and fluffy, using a paddle attachment or electric hand whisk. Gradually add the eggs to the sugar mixture, combining well after each addition. Sift in the flour and baking powder and continue to mix until well combined.

3. Divide the cake mixture equally between the prepared cake tins and bake for 30–35 minutes, until well risen, golden brown and springy to the touch. Remove from the oven and leave to cool for a few minutes before turning out onto cooling racks and leaving to cool completely.

4. For the buttercream, beat the butter for 5 minutes (either using an electric hand whisk or a freestanding mixer fitted with a paddle attachment). Add the icing sugar in batches, mixing well between each addition. Once combined, add a tablespoon of milk and combine until smooth, adding a little more milk if the buttercream is too stiff. Transfer a quarter of the buttercream to a separate bowl and add a drop of the red food colouring to it. Mix until an even colour, adding more red colouring if a darker colour is required. Leave the other larger bowl of buttercream white.

5. When the cakes are completely cool, use a large serrated knife to remove any domed tops from the cakes. Ideally the cakes should be completely flat on top. Using a 8–9cm/3¼–3½in round pastry cutter, cut out the centre from three of the cakes (alternatively use a bowl or glass as a guide). The holes need to be in the same place on each cake to create the cavity which will be filled with sweets.

6. To arrange the cakes, set aside the uncut cake. Place one cake (with a hole in it) on a cake board, stand, or flat serving plate. Top with a layer of white buttercream and jam. Continue stacking the cakes in the same way, until you have three layers of cake on top of each other (each sandwiched with buttercream and jam) and a cavity in the centre. Fill the cavity with jelly beans and place the final layer of cake on top. Ensure the sides are straight and the top is flat.

7. Crumb coat the cake by spreading a thin layer of the white buttercream all over the sides and top of the cake, using a large palette knife. The whole cake should be covered in a thin, even layer, but it doesn't need to be perfect at this stage. Chill the cake for 15–20 minutes. This will help to seal in the crumbs and make the top coat of icing easier to apply.

8. When ready, decorate the cake by spreading the rest of the white buttercream all over the cake in a smooth even layer, using a cake smoother or a large pallet knife to get it really smooth (don't worry too much about the top as it will be covered with swirls of pink buttercream later). Arrange the sprinkles around the bottom of the sides of the cake, to come about half way up the sides. Chill for about 30 minutes to set the buttercream.

9. Place the pink buttercream into a large piping bag fitted with a large star nozzle. Pipe swirls of pink buttercream all over the top of the cake. Top each swirl with a chocolate shape. Decorate the top of the cake with more sprinkles.