In a double boiler, melt both butter and chocolate together and stir until the mixture is thoroughly combined.

While waiting for the butter and chocolate to melt, brush a cake pan with some margarine.

Once the butter and chocolate are melted, add sugar and stir it with wooden spoon.

Add egg into the mixture and stir well.

Preheat the oven.

Next, sift the flour, baking powder and salt into the mixture or batter and then stir well until all the mixtures are well combined.

Pour the batter into the cake pan and bake until a toothpick inserted comes out clean.

Let it cool and serve!