Preheat the oven to 180C/350F.

Peel the apples, then core them. I do this by slicing the peeled apples into quarters and removing the core at an angle. Chop the apples into roughly inch sized chunks.

For the plums, cut them in half and twist to separate the flesh, revealing the seed. Deseed the plum and chop into small chunks. There is no need to remove the skin of the plums, they will soften and help hold the plum's structure when baked.

Toss both fruit together in a large mixing bowl. Set aside.

In a separate small bowl, mix together the caster sugar, nutmeg, cardamom and cornflour. Toss this mixture in the larger bowl with the fruit until the fruit is well coated. Tip into the pie dish, press down into an even layer and set aside for the apples and plums to macerate whilst making the crumble topping.

In the same mixing bowl, place the flour and oats. Stir together to combine.

Rub the butter into the flour mixture until it resembles breadcrumbs.

Stir in the dark muscovado sugar. The topping mixture should be forming thick clumps in the bowl.

Sprinkle the crumble topping over the fruit, pressing downs slightly as required and spreading out evenly over the filling.

Bake the crumble for 45-50 minutes. The crumble topping will be golden and crisp and some of the filling will be bubbling up around the edges of the topping.

Rest the crumble (once removed from the oven) for five minutes before serving. Enjoy on its own, or with ice cream, double cream or custard!