Place butter and milk in a saucepan large enough to mix all the ingredients heat until buter melts

Cool to room temp, add eggs, castor sugar sifted flour, lemon zest and baking powder to the saucepan and heat with a hand-held mixer on low speed until combined, increase speed to medium and heat for 2 minutes until smooth

Pour mixture in a baking.pan bake at 180:-)C and bake for 40 minutes