Spiced quince and ginger upside-down cake with caramel custard

Method

1. Squeeze some lemon into a large bowl of cold water. Peel, quarter and core the quinces, then cut them into 2cm thick wedges, dropping the wedges into the water as you go to stop them discolouring. Heat the oven to 180°C/160°C fan/gas 4. Put the 175g sugar and 4 tbsp cold water in a large nonstick frying pan or shallow flameproof casserole and dissolve the sugar over a low heat. Bring to the boil and cook for 5 minutes until you have an amber coloured caramel. Remove from the heat, add 50g of the butter (be careful – it might spit) and swirl the pan until it has melted and mixed in.
2. Drain the quince slices, dry them well on a clean tea towel, then add them to the pan, cut-side down. The caramel mixture will turn to toffee but don’t worry – the fruit will gradually release their juices as they cook and dissolve it again. Cook them for 5 minutes, then carefully turn the pieces over and cook for another 5 minutes until they are just tender when pierced with a sharp knife. They’ll soften further while the cake bakes.
3. Using two forks, carefully lift out the slices of quince and arrange over the base of a lightly buttered, shallow, round 23cm cake tin (the most heavy duty one you have). You can do this neatly like the spokes of a wheel, or leave the slices higgledy-piggledy. Return the pan of caramel syrup to the heat and bubble until it has reduced and thickened again. Pour the mixture over the quinces and leave to cool.
4. For the sponge, sift the flour, spices and salt into a bowl. Beat the remaining 125g butter with an electric mixer until pale and fluffy. Add the muscovado sugars and orange zest, beat for 3 minutes until paler in colour, then gradually beat in the eggs one at a time, adding a good tablespoon of the flour mixture with each egg. Beat in the golden syrup, grated ginger and vanilla paste/extract. (You can do all this beating with a wooden spoon if you’re feeling energetic – it will take longer…)
5. Add half the remaining flour mixture and gently mix in. Mix the bicarbonate of soda with 2 tbsp boiling water, beat into the mixture, then mix in the remaining flour. Don’t worry if the batter looks a little curdled. Pour it over the quinces, then bake for 15-20 minutes until the top of the sponge is well coloured. Lay a loose sheet of lightly buttered foil over the top of the tin, lower the oven temperature to 170°C/150°C fan/gas 3 and cook for 35-40 minutes until a skewer pushed into the centre of the cake comes out clean. Leave to cool in the tin for 10 minutes.
6. For the caramel custard, slowly dissolve 150g of the caster sugar in 80ml cold water over a low heat, then boil to a rich, amber coloured caramel. Remove from the heat, add the cream (be careful – it may spit), return to a low heat and stir until smooth and creamy. Add the milk, stir, then slowly bring back to the boil. Whisk the egg yolks, the remaining 100g caster sugar and vanilla bean paste or extract in a bowl until thick and pale. Whisk in the hot milk mixture, then return the mixture to the pan and cook gently, stirring, until the custard has thickened – it should coat the back of the spoon. Stir in the rum if using and keep warm.
7. Turn the cake out onto a plate and serve with the warm custard.