We have lots of varieties of plums in the UK, from large Victorias to small greengages. You can use any variety for this dish, or a mixture. Cobnut trees are pretty specific to Kent; if you are unable to get hold of any cobnuts, use hazelnuts instead.
12-18 Victoria or other plums, depending on size
6tbsp caster sugar
For the topping
2tbsp plain flour
40g hard butter, chopped into small pieces
tbsp brown sugar
24–30 cobnuts, shelled and roughly chopped
Clotted cream or thick Jersey cream
Preheat the oven to 200C/gas mark 6. First make the topping: put the flour and butter into a bowl and rub together with your fingers to a breadcrumb-like consistency. Stir in the brown sugar, then mix in the oats and cobnuts. Spread out on a baking tray.
Halve the plums, place cut-side up on another baking tray and sprinkle with the caster sugar.
Place both of the trays in the oven and bake for 15-20 minutes until the plums are lightly coloured and softened and the topping is golden; you may need to take the topping out before the plums.
Leave the plums to cool slightly, then transfer them to individual serving bowls and spoon over the cooking juices.
Scatter over the cobnut topping and finish with a generous dollop of cream.