Step 1

Preheat oven to 375 degrees F.

Step 2

In a large bowl, gently combine blackberries, sugar and all-purpose flour. Transfer to an 8 x 8 baking dish.

Step 3

For the crumble topping, combine all ingredients in a medium bowl and work together with your hands until the ingredients resemble a crumble.

Step 4

Sprinkle the crumble topping over the blackberry mixture. Bake crumble until the the topping is golden brown and blackberries are bubbling, about 40 minutes. Let cool for 15 minutes before serving. Serve warm or at room temperature, with ice cream if desired.