Step #2 Preheat oven at moderate temperature (180C/350F).
Step #3 2.
Step #4 Grease a 23 cm round cake tin & line the bottom with baking paper.
Step #5 3.
Step #6 Beat the eggs & sugar together until creamy - about 5 mins.
Step #7 4.
Step #8 Meanwhile, & then placing the chocolate in a heat-proof bowl & putting it over the pot of boiling water, removing it from the heat, melt the chocolate by microwaving it according to instructions (about 2 mins on low setting - checking & stirring frequently) or by boiling a pot of water, stirring until the chocolate melts (make sure the chocolate bowl does not touch the boiling water in the pot).
Step #9 5.
Step #10 When the chocolate has melted, add it to the egg & sugar mixture & mix together.
Step #11 6.
Step #12 Add the Grand Marnier & cinnamon to the mix & stir.
Step #13 7.
Step #14 Fold the cream into the chocolate mixture.
Step #15 8.
Step #16 Pour the mixture into the prepraed cake tin, & bake for one hr, or until an inserted metal skewer comes out clean.
Step #17 9.
Step #18 Cool in the tin, then turn out onto a wire rack when cool.