Martha Stewart Blackberry Crumb Bars

Martha Stewart blackberry crumb bars are a tender, buttery dessert bar with fresh blackberries and a crunchy brown sugar topping that comes together in 50 minutes. This easy dessert fits summer picnics, potlucks and cookouts, since you cut it into 16 squares you can carry anywhere.

Chill the crumb topping while you mix the cake batter, because the cold butter keeps it nubbly instead of melting flat. Skip the chilling and the topping bakes into one greasy layer.

Martha builds the bars on a soft butter cake, so you get cake, tart fruit and crunch in every bite instead of a loose crumble. A parchment overhang on two sides then lets you lift the whole slab out and cut clean squares.

Martha Stewart Blackberry Crumb Bars

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Course: DessertCuisine: AmericanDifficulty: Easy

Servings

16

servings

Prep time

10

minutes

Cooking time

45

minutes

Calories

210

kcal

A soft vanilla butter cake holds a layer of juicy blackberries under a chilled, crumbly brown sugar topping. After a full cool in the pan, the squares slice clean and stay easy to carry.

Ingredients

• 6 tablespoons unsalted butter melted, and ½ cup (1 stick), room temperature, plus more for pan
  

• 1 3/4 cups all-purpose flour (spooned and leveled), plus more for pan
  

• 1/2 cup packed light-brown sugar
  

• 1/2 teaspoon salt
  

• 1/2 teaspoon baking powder
  

• 1 cup confectioners' sugar
  

• 1/2 teaspoon pure vanilla extract
  

• 2 large eggs
  

• 2 containers (5 ounces each) blackberries
  

Directions

• Prep the pan: Preheat the oven to 350°F and butter an 8-inch square baking pan. Line the bottom with parchment, leaving an overhang on two sides, then butter and flour the paper and tap out the excess.
• Make the topping: Whisk 6 tablespoons melted butter, 1/2 cup packed light brown sugar and 1/4 teaspoon salt in a medium bowl. Add 1 cup flour and mix with a fork until large moist crumbs form, then refrigerate it until you need it.
• Mix the dry ingredients: Whisk the remaining 3/4 cup flour, 1/2 teaspoon baking powder and the remaining 1/4 teaspoon salt in a medium bowl. Set it aside while you start the batter.
• Beat the batter: Beat 1/2 cup room-temperature butter, 1 cup confectioners' sugar and 1/2 teaspoon vanilla with an electric mixer until light and fluffy. Add the 2 eggs one at a time, beating well after each, then mix in the flour mixture on low speed.
• Layer the bars: Spread the batter evenly in the prepared pan. Sprinkle the 2 containers of blackberries over the top, then scatter the chilled topping over the fruit.
• Bake the bars: Bake for 40 to 45 minutes. They're ready when the top is golden and a toothpick in the center comes out with moist crumbs attached.
• Cool and cut: Cool the bars completely in the pan so they set. Then lift the cake out by the paper overhang and cut it into 16 squares.

Tools for this recipe

• USA Pan 8x8 square cake pan, Reynolds unbleached parchment paper, KitchenAid 5-speed hand mixer, Nielsen-Massey Madagascar Bourbon vanilla extract, 8 oz. As an Amazon Associate I earn from qualifying purchases.

FAQs

How do I store blackberry crumb bars?

Pack them in a sealed container and leave them on the counter, where they stay good for up to 3 days. The bars are made for picnics, so they travel well in that same container.

Can I use frozen blackberries instead of fresh?

Yes, but don't thaw them first, since thawed berries bleed purple juice into the batter. Scatter them on frozen and expect a few extra minutes in the oven.

Can I make the topping ahead of time?

Yes, you can mix the crumbs up to a day ahead and keep them covered in the fridge. Colder crumbs bake up nubbier, so it only helps.

What can I use instead of an electric mixer?

A sturdy whisk or wooden spoon works if your butter is truly room temperature and soft. Beat it with the confectioners' sugar for a few extra minutes until it looks pale and fluffy.

Why did my crumb bars come out soggy in the middle?

Cutting them before they cool is the usual cause, because the fruit juices haven't set yet. Wait until the pan is completely cool, and check that the toothpick shows only moist crumbs.