In one bowl, mix together flour, baking powder, salt and bicarbonate of soda.

In another bowl, using the electric hand mixer, beat together melted butter and sugar until light and creamy. Then add eggs one at a time until creamy.

Pour the mixture into the greased baking tray and bake at 180 degrees centigrade for 25-30 minutes, or if the knife comes out clean when inserted in the centre of the brownie.