Blackberry Buttermilk Cake

Ingredients

• 1.5 teaspoons double-acting baking powder 
• 0.5 teaspoon baking soda 
• 10 ounces blackberries fresh
• 1 cup buttermilk well-shaken
• 2.3 cups cake flour plus more for pan sifted (, then measured)
• 3 large eggs room temperature
• 1.5 teaspoons orange zest finely grated
• 0.8 teaspoon salt 
• 0.3 cup sugar 
• 0.8 cup butter unsalted plus more for pan and parchment room temperature ()
• 2 teaspoons vanilla extract 

Equipment

• bowl
• frying pan
• baking paper
• oven
• knife
• wire rack
• hand mixer

Directions

1. Position a rack in middle of oven and preheat to 350°. Butter pan; line bottom with a round of parchment paper. Butterparchment. Dust with flour; tap out excess. Arrange berries in a single layer in bottom of pan; sprinkle evenly with 1/4 cup sugar.
2. Sift 2 1/3 cups flour, baking powder, salt, and baking soda into a medium bowl; set aside. Using an electric mixer, beat 3/4 cup butter and remaining 1 1/3 cups sugar in a large bowl at medium-high speed, occasionally scraping down sides of bowl, until pale and fluffy, about 2 minutes.
3. Add eggs, one at a time, beating well after each addition. Beat in vanilla and zest. Reduce speed to low; beat in flour mixture in 3 additions, alternating with buttermilk in 2 additions, beginning and ending with flour mixture and beating just until incorporated.
4. Pour batter over berries in pan; smooth top.
5. Bake until cake is golden brown and a tester inserted into the center comes out clean, about 1 hour 25 minutes.
6. Let cool in pan set on a wire rack for 15 minutes, then run a thin, sharp knife around edge of pan to loosen.
7. Remove pan sides. Invert cake onto rack and remove pan bottom; peel off parchment. Dust top generously with powdered sugar and let cool completely.