1. For the pears: melt the butter in a 20-25cm ovenproof frying pan over a medium heat. Stir in the sugar and heat for 2-3 minutes, stirring continuously, until the sugar has dissolved and the mixture has turned a light golden-brown colour.

2. Remove from the heat and scatter the sliced pears over the caramel sauce, then dot the chocolate pieces in amongst the pears. Set aside.

3. For the sponge: sift the cocoa powder, flour, bicarbonate of soda and baking powder together into a large bowl.

4. In a separate bowl or jug, mix together the eggs, sugar, buttermilk and vegetable oil.

5. In one go, pour the wet ingredients into the dry ingredients and mix together a few times until just combined (don't over mix or the sponge may become heavy). You can prepare the cake to this stage then store the batter in the fridge for a few hours, or continue with the cake.

6. When ready to bake the cake, preheat the oven to 200C/180C fan/gas 6.

7. Pour the batter into the frying pan over the pears and chocolate, spreading it out to the sides of the pan, and bake for 30 minutes.

8. Remove from the oven and leave to stand in the pan for 5 minutes (don't leave it for longer than this or the caramel will start to set and stick to the pan). To turn out, cover the pan with a large plate and carefully flip it over so the cake is served pear-side up.

9. Serve warm with whipped cream.