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Classic Blackberry Crumble Recipe | Easy Fruit Dessert with Oat Topping

A cozy blackberry crumble with a jammy, bright filling and a buttery oat topping that bakes up golden and crisp. Perfect warm with ice cream and easy to make with fresh or frozen berries.
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Prep Time 15 minutes
Cook Time 40 minutes
Total Time 1 hour 15 minutes
Servings 8 servings

Ingredients
  

Ingredients

  • 6 cups blackberries (fresh or frozen; if frozen, use without thawing)
  • 1/2 to 3/4 cup granulated sugar
  • 2 tablespoons cornstarch (or 3 tablespoons if using very juicy berries)
  • 1 tablespoon lemon juice
  • 1/2 teaspoon lemon zest
  • 1 teaspoon vanilla extract
  • Pinch of fine sea salt
  • 1 cup old-fashioned rolled oats (not quick oats)
  • 3/4 cup all-purpose flour
  • 1/2 cup packed light brown sugar
  • 1/4 cup granulated sugar
  • 1/2 teaspoon ground cinnamon (optional)
  • 1/4 teaspoon fine sea salt
  • 1/2 cup unsalted butter, cold, cut into small cubes
  • 1/2 teaspoon vanilla extract (optional)
  • 2 to 3 tablespoons chopped nuts (pecans or almonds, optional)

Instructions
 

Instructions

  • Heat the oven to 375°F (190°C) and lightly butter a 9-inch square or 2-quart baking dish.
  • Combine the blackberries, granulated sugar, cornstarch, lemon juice, lemon zest, vanilla, and a pinch of salt in a bowl and toss gently until glossy and evenly coated.
  • Spread the berry mixture evenly in the prepared baking dish.
  • In a separate bowl, mix the oats, flour, brown sugar, granulated sugar, cinnamon, and salt.
  • Add the cold butter cubes and vanilla to the dry mixture and work with a pastry cutter or fingertips until moist, clumpy crumbs form; fold in nuts if using.
  • Sprinkle the crumble evenly over the berries, leaving some larger clumps for texture.
  • Place the dish on a lined sheet pan and bake until the topping is deep golden and the filling bubbles thickly around the edges, about 35 to 45 minutes.
  • Let the crumble rest 15 to 20 minutes before serving to allow the filling to set.

Notes

If using frozen blackberries, add 3 tablespoons cornstarch and extend bake time by 5 to 10 minutes if needed. Serve warm with vanilla ice cream, whipped cream, or a drizzle of heavy cream. Leftovers can be kept loosely covered at room temperature up to 6 hours or refrigerated 3 to 4 days; reheat at 325°F (165°C) for 10 to 12 minutes to re-crisp. Freeze up to 2 months and reheat from frozen at 350°F (175°C) until hot and bubbly, 20 to 30 minutes. Use rolled oats, avoid overworking the topping, and bake until bubbling and deeply golden for best texture.