Auntie Valeria's Ciambellone

Ingredients
5 eggs
100 gr butter
1/2 tbs baking powder
200 gr sugar
130 ml milk
1 organic lemon
350 gr flour

Cream the butter and sugar together and add the eggs and some grated lemon skin. Add the flour alternately, a tablespoon at a time, beating in gently and 1/2 tbsp of yeast at the end. Bake in greased and floured round cake tin at 180°C for 30-35 minutes.