Preheat oven to 325 degrees.

Melt the chocolate either in the microwave oven (30 second intervals, stirring between each) or over a double boiler on the stove.

Combine the eggs and sugar with a whisk until light yellow.

Add the melted chocolate, melted butter and liqueur (if using) and stir well to combine.

Pour the batter into a well greased spring form pan.

Wrap the bottom of the pan with foil paper to prevent any water from leaking into the cake pan.

Place the spring form pan (with the foil) in a large roasting dish, and fill the roasting dish halfway with hot water.

Bake in the preheated oven for 35 - 40 minutes.

Allow cake to cool briefly before removing from the spring form pan.

Serve with whipped cream, ice cream, fresh berries, anything that makes you smile!