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Cut squares of Blackberry Butter Cake on a piece of parchment, with a small blue knife and a few fresh blackberries scattered around.

Blackberry Butter Cake

Tender and buttery and bursting with pockets of ripe summer berries, this blackberry butter cake is what I'd call an ideal snack cake—a snackberry cake, if you will—that's easy to prepare and even easier to eat.
Yield: one 8-inch square cake (16 servings)
Prep Time: 20 minutes
Cook Time: 40 minutes
Total Time: 1 hour

Ingredients

  • 7 ounces / 170 g blackberries, washed and dried
  • 1 ⅓ cup / 167 g all-purpose flour, plus more for tossing with the berries
  • ¾ teaspoon baking powder
  • ½ teaspoon fine sea salt
  • ½ cup / 113 g (1 stick) unsalted butter, at room temperature
  • ⅔ cup / 133 g granulated sugar, plus more for sprinkling on top
  • 2 large eggs, at room temperature
  • ½ cup / 120 g sour cream, at room temperature
  • ½ teaspoon baking soda
  • 1 ½ teaspoons vanilla extract
  • ¼ teaspoon almond extract, optional

Instructions

  • Preheat oven to 350 degrees F. Line the bottom and sides of an 8-inch square cake pan with parchment paper; lightly butter parchment.
  • Wash blackberries and spread on a paper-towel lined plate to dry fully.
  • Measure out flour into a small bowl, and whisk with baking powder and salt (baking soda will be used in a different step).
  • In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, cream butter and sugar together until fluffy, 2 to 3 minutes. Add eggs, one at a time, mixing well after each addition.
  • Whisk baking soda into sour cream (I recommend measuring your sour cream with a 1 cup liquid measuring cup, then you can whisk the baking soda right in without dirtying another bowl).
  • Add half of dry ingredients to the stand mixer bowl, and mix on low speed until almost but not quite fully incorporated. Add all of sour cream mixture along with vanilla and almond extracts and mix to combine. Scrape down the sides of the bowl, then add remaining flour and mix on low speed, or by hand, until just incorporated.
  • Toss blackberries with a teaspoon or two of flour until lightly coated (don't do this too far ahead of time or the flour will get gummy).
  • Spread or scoop half of the batter into prepared baking pan, spreading into an even layer. Top with half of blackberries, spacing them out evenly if possible.
  • Dollop remaining batter on top of berries, gently spreading into an even layer with an offset spatula.
  • Top with remaining half of blackberries, positioning them in the spaces between berries from the first layer, especially if your berries are on the large side. Sprinkle generously with a tablespoon or so of granulated sugar.
  • Bake for about 38 to 42 minutes or until top is light golden brown and a toothpick inserted near the center (try not to stick it into a berry) comes out clean.
  • Place pan on a wire rack to cool. Then use the parchment to lift the cake from pan to cool completely before slicing into squares. Cake will keep, covered in an airtight container, for up to 3 days.