Method Chocolate Buttercream Place the butter, icing sugar and salt in a bowl and mix on low, until well combined.

Add the cocoa powder, and mix again on low until mixed through. Then turn mixer to medium speed and mix until light and fluffy. Add vanilla and mix again until well-incorporated, and still soft and fluffy. Spread a thin layer of chocolate buttercream on the bottom of your lined loaf pan (or any other dish that you're using with similar dimensions

Add the milk to a separate bowl. Then place a few cookies in the milk for no more than 3-5 seconds (the cookies should NOT be completely soaked through and disintegrate). Place these cookies in a layer over the buttercream. Spread another layer of chocolate buttercream, followed by the milky Maria cookies.

Repeat until you reach the top, and end with a layer of cookies (this layer should be well packed - and only if you are hoping to unmold the dessert before serving). There should be some leftover buttercream to decorate the outside of the cake. Cover and let it chill in the fridge for at least 3 hours or overnight.