Preheat your oven to 180C/160C Fan, and line three 8"/20cm cake tins with parchment paper.
Add your butter and sugar to a bowl, and beat until light and fluffy. I use my Kitchenaid with the paddle attachment!
Add in your flour, eggs and baking powder and beat again until a lovely smooth cake mixture is formed.
Split evenly between the three tins and bake in the oven for 30-35 minutes (or until a skewer comes out clean!)
Once baked, leave to cool in the tin for 10 minutes, and then leave to cool fully on a wire rack.
For the Buttercream
Beat your butter on its own for a while in your mixer until it's smooth and supple.
Add in your icing sugar a little at a time and beat fully until its light and fluffy!
Add in your Biscoff spread and beat until combined. If its really stiff, add in 1-3tbsp of boiling water mixing fully each time.
For the Ganache
Add your chocolate and cream to a microwaveable bowl, and heat for 15-30 second intervals at half power. Keep going and stiring each time until a smooth ganache is formed.
Alternatively, add your cream to a pan and heat till just before boiling point. Pour over finely chopped chocolate and leave to sit for 5 minutes. Once sat, mix till smooth (Add back to the pan if its not quite melted).
Leave the ganache in a bowl and stir every few minutes till it forms a peanut butter like consistency - you can do this in the fridge as well, just make sure to stir it so it doesn't set too quickly!
For the Decoration
Spread a smidge of buttercream on the cake board, and add your first cake to a cake board (for an 8" cake, I use a 10" board). Spread over some of the buttercream.
Add on the second cake, and repeat!
Add on the third cake - spread some of the buttercream on top and around the edges till the sides are smooth and you have created a crumb coat. It doesn't need to be thick, it just needs to fill any gaps or holes that may be on the sides!
Refrigerate the cake for 10-15 minutes to set the crumb coat.
Keep repeating this till the sides of the cake are smooth and lovely. Set the cake in the fridge again for 10-15 minutes.
Carefully melt down the biscoff spread till drippable, and drip down the sides of the cake and over the top of the cake. Set the cake in the fridge again for 10-15 minutes.
Pipe some swirls of the leftover buttercream on top using a medium 2D closed star piping tip and decorate with the biscuits and crushed biscuits! Enjoy!