Preheat the oven to 375 degrees F.
Place the cherries and peaches in a 9×13 inch baking dish. In a bowl, toss together the sugar, flour, salt and cinnamon. Add it to the fruit and toss well to coat. Sprinkle the butter pieces on to the fruit.
To make the oatmeal crumble, stir together the oats, sugar, flour, cinnamon and salt. Add the softened butter and use your hands to crumble it up and toss it in the mixture – I combine it for a full 5 minutes until it is really incorporated and crumbly – almost the whole mixture is like wet oat-y sand.. Sprinkle it evenly over the fruit.
Bake for 35 to 45 minutes, until the fruit is caramely and the crumble on top is golden. Let it cool slightly before serving with ice cream. Garnish with fresh mint!