1 - SuperValu Vanilla Pod
halved lengthways and seeds scraped out
Heat oven to 180C/160C fan/gas 4 and line and grease 3 x 20cm sandwich tins.
Beat the butter and sugar in a large bowl with an electric whisk until light and fluffy. Add the vanilla extract and the egg whites a little at a time, beating until fully combined before adding more. Mix the flour, cornflour and baking powder together, and add the dry ingredients in 3 goes, alternating with the buttermilk. Divide the batter evenly between the tins.
Bake in the oven for 25-30 mins, until a skewer inserted into the middle comes out clean. Allow them to cool for 10 mins before turning out onto a wire rack, peeling off the parchment. Cool completely.
To make the buttercream, put the egg whites and sugar in a big bowl with the vanilla seeds and set over a pan of gently simmering water. Lightly whisk until the sugar has fully dissolved – when you can’t feel any grains of sugar, the mixture is ready. Remove the bowl from the heat and keep whisking until a thick meringue has formed. Continue whisking until the meringue has cooled to room temperature, then slowly add in the butter, 1 tbsp at a time. By the time all the butter has been incorporated, the mixture should be a silky-smooth buttercream. If it isn’t, continue to whisk until it is. If it still refuses to thicken, the mixture may be too warm, so chill for 10 mins, then continue whisking. Add the vanilla extract and mix.
To assemble, place a sponge on a cake board or serving plate and top with a thin layer of buttercream. Repeat with the remaining cake layers and finish by spreading the remaining buttercream over the top and sides of the cake using the edge of a palette knife to give a smooth finish.
To decorate the cake, cover with multi-coloured sprinkles.