Put the milk chocolate and dark chocolate in a heatproof bowl.

Melt in the microwave in 30 second bursts, stirring between each blast and taking care not to overheat the chocolate. When there are only a few solid pieces left, you can stop heating as they will melt from the residual heat.

Stir in the Biscoff spread and set aside to cool.

Put the eggs, buttermilk, vanilla, butter and sugar in a large bowl. Whisk until everything is combined.

Add the melted chocolate and Biscoff mixture and whisk again.

Sift in the flour and bicarbonate of soda. Fold together,

Immediately divide the mixture between the three prepared tins and level off.

Put the tins in the oven - you may need to use two shelves. Bake for 25-30 minutes until risen and firm to the touch.

Allow the cakes to cool in their tins for minutes before removing from the tins and transferring to a wire rack to cool completely.

If any of the cakes have domed on top, you can trim them flat with a sharp, serrated knife.

Put the butter, icing sugar, salt, Biscoff spread and milk in a large bowl and whisk until pale and creamy.

Place the first sponge on a board.

Transfer your buttercream to a piping bag fitted with an open star tip and pipe rosettes all over the surface, using about one third of the buttercream, or simply spread with a palette knife.

Put the next cake on top and top with another third of the buttercream in the same way.

Position the final cake on top, then top with the final third of the buttercream.

Lightly warm the Biscoff smooth spread for about 5-10 seconds in the microwave, just enough to make it runny, then drizzle over the top of the cake.

Crumble Biscoff biscuits and scatter over the top.