Preheat the oven to 180 C / Gas 4. Grease the savarin tin with a good layer of butter.
Mix the sugar, butter and margarine together until smooth. Gradually add the flour and egg a little at a time, mixing all the time for a good 5 minutes.
Then fold in the cherries, ground almonds and lemon zest until all ingredients are covered. Add the mixture into the tin and spread out evenly using the back of your hand. It helps to dip your hand in cold water, it stops the cake mixture sticking to you.
Bake in the preheated oven for 40 minutes. Test with a knife, if the knife comes out clean it's ready. Tip out upside down onto a cooling tray.
For the icing, mix 3 or 4 drops of the lemon juice to the icing sugar. Once the cake is cool, with a piping bag or a fork, drizzle the icing around the cake a bit. Place the cherries and baked nuts on top and a few on the plate.