In a small bowl, combine oats, flour, cinnamon, a generous pinch of salt, and sliced butter. Mix and work the butter into the dry ingredients by continually squeezing butter into the oat mixture.
Sprinkle the crumble topping evenly over the fruit and bake for 25-35 minutes, until topping is golden brown and fruit is bubbling. Enjoy warm with ice cream or fresh whipped cream.