Plum upside-down cake

Method

1. Heat the oven to 180ºC fan/ gas 6. Grease the cake tin with butter and line the base and sides with baking paper. Put 150g of the sugar in a pan over a low-medium heat to melt, swirling the pan instead of stirring. Once it begins to turn golden, add the honey, 3 of the thyme sprigs and the salt. Remove from the heat, allow to cool slightly, then pour into the lined cake tin. Move the thyme sprigs into the centre of the tin. Arrange the halved plums, cut-side down, in a single layer on top (chop one or two, if needed, to fill in gaps and cover the base).
2. Beat the 125g butter with the remaining sugar until pale and creamy, then add the eggs one at a time, beating the first into the mixture before adding the next. Sift together the flour and baking powder, then gently fold in with the hazelnuts using a balloon whisk. Strip the leaves off the remaining thyme sprigs and fold those through too. Pour the mix over the plums, smooth the top, then bake in the oven for 45-50 minutes until a skewer pushed into the centre comes out clean.
3. Leave to cool for 5 minutes, then carefully invert the cake onto a plate. Peel away the baking paper, then cool for 5 minutes before slicing.