Grease and line the bottom of 3 x 20cm (8 inch) sandwich tins.

Preheat the oven to 180C (160C fan-assisted / 350F).

Put the sugar and butter in a bowl and beat together until very pale and fluffy.

Whisk in the eggs, Biscoff spread, milk and vanilla.

Fold in the flour and salt until combined into a thick batter.

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.

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.

Allow to set somewhere cool for 15 minutes before cutting into generous squares to serve.