Cream the butter and sugar together in a mixing bowl until pale and fluffy.
Gradually mix in the beaten egg, then the milk and finally the flour.
Grease a microwaveable bowl with butter. Place the fudge and chocolate into the bowl. Spoon the sponge mixture on top and microwave for about 4-5 minutes on full power.
Meanwhile, for the chocolate sauce, heat the chocolate and cream together in a pan over a low heat, stirring continuously until combined.
Turn the sponge pudding out onto a plate and serve drizzled with the hot chocolate sauce.
