Preheat the oven to 350 degrees Fahrenheit.

In a medium bowl, mix flour, oats, brown sugar, and cinnamon (if using). Add butter and salt, then cut with a fork or pastry cutter.

Spread the crumble in a 10-12 inch skillet or an 11x7 baking dish.

Bake for 18-20 minutes or until golden brown.

Serve with salted caramel, sea salt flakes, and a scoop of vanilla bean ice cream. Enjoy the deliciousness!