To make the crumble topping, combine the flour, oats, powdered seaweed and sugar in a bowl. Add the butter and rub in lightly with your fingertips until the mix resembles coarse breadcrumbs.

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Preheat your oven to 200°C (180°C fan). First, make the crumble topping. Cut the butter into small cubes. Mix the flour and sugar together in a large bowl, then add the cubes of butter.

5. Spread the apple and blackberry mixture on top, then sprinkle the remaining third of the crumble mix over the top (don’t worry if there are gaps, you want to see the fruit coming through).

At this stage mix the granulated sugar. Place the soft fruit in an earthenware dish and top with the crumble mixture and bake in a preheated oven 200’c/ 400’F/gas mark 6 until hot and golden ...

And when it comes to dessert ... old-school recipe – and wholeheartedly approve of making good use of in-season fruit – there’s no reason why you can’t customise your crumble.

John Whaite has a treat in store for you this weekend. Using fresh seasonal fruit he makes his blackberry and ginger crumble cake. For the cake, cream the butter and sugar until pale and fluffy ...