Preheat the oven to 180°C.
Heat a pan and cook the plums in 40g of butter for 2-3 minutes until softened.
Add the brandy and carefully flambé it to burn off the alcohol.
Add cinnamon, star anise, and cloves, then simmer for 3-4 minutes until plums break down.
Grease four 7.5cm chefs' rings and seal the bottoms with aluminium foil.
Place rings on a tray and pack the plum mixture into the bottom.
Rub 175g of butter into the sugar until the mixture looks like breadcrumbs.
Stir in the flour to finish the crumble and sprinkle it over the plums.
Bake for 15 minutes until golden and bubbling.
Whisk egg yolks, sugar, and brandy together for the custard.
Simmer milk, cream, and vanilla in a pan for one minute.
Combine the hot milk mixture with the egg mixture and whisk well.
Thicken the custard over low heat while stirring constantly.
Remove the vanilla pod from the thickened custard.
Unmold the crumbles onto plates and serve with custard and clotted cream.