Heat the oven to 350F. Grease a 9x13inch cake pan and line with baking paper.

In a large bowl mix all the dry ingredients and spice mix together. In another bowl whisk all the wet ingredients together. Add the wet ingredients to the dry ingredients and fold in until just combined.

Pour the batter into the cake pan and bake until a toothpick into the middle comes out clean, checking for doneness at 20mins. Allow to cool for 15mins and then transfer to a cooling rack. Let cool completely before icing.

Frosting

Beat butter, cream cheese and speculoos with electric whisk on medium till light and fluffly.

Turn down to low and slowly add the icing sugar until fully mixed in. Turn up to medium high and beat till light and fluffy.

To assemble

Cut out the mini cakes with a 2-2.5inch round cutter trying to get as many cakes as possible. Fill a piping bag with the frosting, pipe a layer of frosting on half the rounds, top each with another round and pipe another layer of frosting on top.