1. Place all the ingredients under cake into a bowl and mix to a smooth batter beat for 1-2 minutes.
2. Divide the mixture between 12 well greased mini loaf tins.
3. Bake in a preheated oven 180°C (360°F, Gas Mark 5) for 20-22 minutes until golden in colour and firm to the touch.
4. Allow to cool completely before decorating.
5. Sift the icing sugar into a bowl and add the butter, then beat until smooth and creamy for about 4-5 minutes with an electric whisk or food processor.
6. Beat in the lager, making sure you do not add too much to make it runny.
7. Split each loaf cake into two horizontally in the middle.
8. Pipe or place the buttercream on the bottom half of each loaf cake and then place the other piece on top.
9. Make up the drizzle with the icing sugar and lime juice.
10. Drizzle over the cakes and sprinkle with the lime zest.