Step 1

Generously oil a 1 litre/1¾fl oz microwaveable pudding basin (it should have a diameter of around 17cm/6½in at the rim – see recipe tips below). Cut a small circle of baking paper and place in the bottom of the basin – this will make it easier to remove the sponge.

Step 2

Put 200g/7oz of the cake mixture in a bowl and add an egg and 4 tablespoons cold water (or follow the packet instructions for when using half a packet of the mixture). Whisk with electric beaters for 2 minutes, or by hand until well combined and creamy. Stir in the orange zest.

Step 3

Spoon the batter into the prepared basin, ensuring the mixture doesn’t rise more than half of the way up the dish or it could rise and bubble over the sides.

Step 4

Cook, uncovered, on HIGH for 3 minutes 30 seconds in an 800W microwave oven or 2 minutes 50 seconds in a 1000W microwave oven. The sponge should be well risen, just firm to the touch and a little gooey around the edges. (Microwave ovens vary so the timings above are a guide. Be prepared to adjust if yours is more or less powerful than the ones in the timings above.)

Step 5

Take the pudding out of the microwave, using an oven cloth as it will be hot, and leave to stand while the sauce is made.

Step 6

To make the sauce, put the chocolate in a microwaveable bowl and cook on HIGH for 1 minute. Stir and then cook on HIGH for a further 20–30 seconds, or until the chocolate is very soft but not completely melted. Don’t allow to overheat or it burn. Stir until smooth.

Step 7

Turn the pudding out onto a plate. Peel off the baking paper and pour the warm chocolate over the top. Decorate with extra orange zest if you like. Serve with custard, cream or ice cream.