Preheat the oven to 375 F/ 190 C/ gas mark 5.Cook cherries: Start by making the cherry filling. In a skillet/pan cook the cherries for a few minutes squashing the fruit with the back of a spoon until they release lots of juice. Stir in the jam and flour and cook for another minute or so until the mixture starts bubbling up.
Pour mixture: Pour the cherry mixture into your oven dish.
Make crumble: To make the crumble topping combine the ground almonds with the oats, butter and sugar. Rub together using your fingertips and the palms of your hands until crumbly.
Scatter crumble: Stir in the almond flakes then scatter the mixture over the fruit without pressing down.
Bake crumble: Bake in the centre of the oven for 25-30 minutes until golden brown. Remove from the oven and serve immediately.
Notes
I used frozen rather than fresh cherries because frozen come already pitted! But if you prefer to use fresh cherries and don't mind spending a little extra time removing the stones that's absolutely fine too. They will probably only need about 3 minutes in the pan (rather than 5 as with frozen).
You can make the crumble topping by hand or in a food processor.
You can prepare the crumble ahead and refrigerate for several hours before popping in the oven (ensure the filling has cooled before covering with the crumble mixture).
I used ordinary rolled oats but you can use jumbo rolled oats for a coarser crumble.
You can add seeds into the crumble topping mixture such as sunflower, chia and/or flaxseed.
Best served hot on its own or with a dollop of natural or flavoured yogurt.
Freeze the crumble uncooked, covered, for up to 3 months.