Blackberry Crumb Cake

Blackberry Crumb Bars

This Blackberry Crumb Cake will “delight picnic-goers with a portable version of summer berry crumble: a perfect marriage of tart fruit and tender cake, capped with a slightly crunchy topping.” Martha Stewart

Blackberry Crumb Cake 

Print This Recipe Total time Yield 16Source Martha Stewart LivingPublished

While you prepare the cake, refrigerate the crumb topping. This will help give it a nubbly texture once baked. 

To store the cake, keep in an airtight container at room temperature, up to 3 days.

Blackberry Crumb Bars


  • 6 tablespoon unsalted butter melted
  • 8 tablespoon unsalted butter room temperature
  • 1 3/4 cup all-purpose flour (spooned and leveled) divided, plus more for pan
  • ½ cup light-brown sugar packed
  • ½ teaspoon kosher salt
  • ½ teaspoon baking powder
  • 1 cup confectioners’ sugar
  • ½ teaspoon vanilla extract
  • 2 large eggs
  • 10 ounce fresh blackberries (about 2 containers)


Set the oven rack in the center position. Preheat oven to 350 degrees. Butter an 8‑inch square baking pan. Line bottom with parchment paper, leaving an overhang on two sides; butter and flour paper, tapping out excess.

Make topping: In a medium bowl, whisk together melted butter, brown sugar, and ¼ teaspoon salt; add 1 cup flour, and mix with a fork until large moist crumbs form. Refrigerate topping until ready to use. 

In a medium bowl, whisk together remaining 3/4 cup flour, baking powder, and remaining ¼ teaspoon salt; set aside. In a large bowl, using an electric mixer, beat room-temperature butter, confectioners’ sugar, and vanilla until light and fluffy; add eggs, one at a time, beating well after each addition. Reduce speed to low; mix in flour mixture. Spread batter evenly in pan; sprinkle with blackberries, then chilled topping.

Bake until golden and a toothpick inserted in center comes out with moist crumbs attached, 45 to 50 minutes. Cool completely in pan. Using paper overhang, lift cake onto a work surface; cut into 16 squares.