This makes just one tier of a wedding cake!
Line 3 cake tins (20cm diameter) with baking paper and preheat the oven to 180°C. Melt the white chocolate for the cake in a bowl over a pan of steaming water or in a microwave then leave to one side for later.
Beat the butter and sugar together in a large bowl or kitchen mixer until light and fluffy. Crack in the eggs one at a time as you beat, including a heaped tablespoon of the flour every 2 eggs. Sieve the rest of the flour into the bowl with the baking powder and gently mix it into the wet ingredients, folding to avoid knocking out all the air you’ve just beaten in. Fold in the buttermilk, followed by the melted white chocolate and cardamom powder.
Divide the mixture between the 3 cake tins. Bake for 35 minutes. Remove the cakes from the oven once baked, risen and when the sponge bounces back when lightly pressed. Leave to cool completely, on a wire rack. Peel back the baking paper and trim each cooled sponge so that they’re flat, neat and even.
Beat the butter and icing sugar together in a bowl until soft and smooth. Melt the chocolate for the buttercream over a pan of water or in a microwave. Leave to cool for 15 minutes. Beat the milk and white chocolate into the buttercream and transfer to piping bags.
Pipe the buttercream onto the cooled sponges, starting from the centre of the sponge and working outwards. Mash the fresh raspberries into the cloudberry jam, squeeze in a little lemon juice and spread the mix over the buttercream on top of 2 of the sponges.
Place the sponge layers on top of each other, keeping the stack even and finishing with the sponge that has no jam on it. Spread a thin layer of the buttercream around the cake to crumb coat it and chill for a few hours in the fridge.
Coat the cake with a second layer of buttercream and chill for another few hours then decorate with macarons.