Beat your softened butter and sugars for a few minutes on a medium setting, until soft and an easily spreadable consistency.
Sift together your flour, baking powder, salt and cinnamon.
Add your eggs and vanilla extract to the butter and sugar mixture.
Add 3 heaped desert spoonfuls of the flour mixture.
Beat on a medium setting until just combined.
Add the rest of your flour and beat for 10-20 seconds on medium-high until fully mixed in.
Scrape down your bowl with your spatula to ensure all of the mixture from the sides and base is incorporated.
Add the cake mixture to your prepared tin and even out with the back of a large spoon.
Bang the cake tin on onto the kitchen counter to ensure any larger air pockets are removed.
Bake in the centre of your oven for 25 minutes or until a skewer inserted into the centre comes out clean.
Allow to cool in the tin on a cooling rack for 10 minutes.
Place the cooling rack on top of the cake and flip over, to remove from the tin.
Take a baking nozzle (or sharp knife) and cut holes through the cake in 4x5 rows. Just go down a centimetre. Remove the piece of cake and set this aside.
Melt your Biscoff spread in your microwave for about 10 seconds, just so it isn't stiff.
Fill the holes with Biscoff Spread and replace the cut out cake piece as a lid.
Leave your cake to cool completely.