1. Preheat the oven to 175C. Grease and line the base and sides of the tin or tins with non-stick baking paper.
2. To make the cake, beat the butter and sugar in a large bowl until light and fluffy.
3. In a separate bowl, combine the flour and baking powder. Add the eggs a little at a time to the creamed butter and sugar. 
4. Follow each addition with a scoop of flour, mixing well after each addition until all the eggs and flour are mixed in.
5. Stir in the lemon juice and spoon the mixture into the prepared tin or tins.
6. Scoop a small hollow into the top of the mixture and place in the oven. A 20cm cake will take approximately 1 hour and 20 minutes to cook - smaller cakes will cook more quickly.
7. A skewer inserted into the centre should come out clean when the cake is cooked. Cool the cakes in the tins for 10 minutes before tipping onto a rack.
8. To make the frosting, beat the butter until pale and fluffy. Sift in the icing sugar a little at a time, beating well after each addition.
9. Add the lemon zest of two lemons and begin adding juice to taste. Sift in a big spoonful of icing sugar after each addition of juice to keep the texture of the frosting light and fluffy. 
10. Continue until the desired lemony flavour is achieved.

Cook's Tips

To assemble a tiered cake, trim the pointed tops off the cakes and invert - the bottoms are smoother and less inclined to crumb. Stack the cakes, beginning with the largest cake, and insert a wooden skewer through the middle of the cakes to secure the stack. Trim the skewer so that the end is flush with the top of the stack. Starting at the top, generously coat the cakes with frosting, working your way down. When the cake is roughly coated, refrigerate to firm the icing up, then smooth the icing using a long metal spatula or palette knife dipped in hot water.

Refrigerate until firm before decorating with ribbon and flowers. Keep refrigerated until required.

To make frosting for a three-tier cake, use 300g butter and 4½ cups icing sugar.