Blueberry-Ginger Buckle

A buckle is a delicious treat filled with so much fruit that it starts to buckle, thus the name, and this Buckle is sure to be your next favorite. The combination of the zing of ginger and sweetness of berries pair together to create a flavor like no other.

INGREDIENTS

8 Tbsp. unsalted butter, room temperature, divided, plus more for pan
½ cup (63 g) raw pecans or walnuts
2¼ cups (281 g) all-purpose flour, divided
¼ cup (packed; 50 g) dark brown sugar
½ tsp. ground ginger
1¼ tsp. Diamond Crystal or ¾ tsp. Morton kosher salt, divided
1 tsp. baking powder
¼ tsp. baking soda
1 2″ piece ginger
⅔ cup (133 g) granulated sugar
2 large eggs
½ cup sour cream
1 tsp. vanilla extract
2½ cups (325 g) fresh or frozen conventional or wild blueberries

DIRECTIONS

Place rack in middle of oven; preheat to 350°. Lightly butter an 8×8″ or 9×9″ baking pan, then line with overlapping pieces of parchment paper, leaving overhang on all 4 sides. Lightly butter parchment.
Make the topping. Coarsely chop ½ cup (63 g) raw pecans or walnuts. Combine ¾ cup (94 g) all-purpose flour, 4 Tbsp. unsalted butter, room temperature, ¼ cup (packed; 50 g) dark brown sugar, ½ tsp. ground ginger, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt in a small bowl. Using a fork or your fingers, smash butter into dry ingredients until mixture is homogeneous and no streaks of butter remain. Add pecans and mix until clumps form. Cover and chill streusel while you make the batter.
Whisk 1 tsp. baking powder, ¼ tsp. baking soda, remaining 1½ cups (188 g) all-purpose flour, and remaining ¾ tsp. Diamond Crystal or ½ tsp. Diamond kosher salt in a medium bowl. (You can also do this in an airtight container—just combine everything, cover, and shake!)
Peel one 2″ piece ginger (a spoon makes this easy work). Using a Microplane, finely grate ginger into the bowl of a stand mixer, or a large bowl if using a hand mixer. (Try to avoid adding any of the really stringy bits and compost those.) Add ⅔ cup (133 g) granulated sugar. If using a stand mixer, fit with paddle attachment. Beat on low speed until sugar is moist and fragrant and no large clumps remain. Add remaining 4 Tbsp. unsalted butter, room temperature, increase speed to medium-high, and beat, scraping down sides of bowl 2–3 times, until very pale and fluffy, about 5 minutes.
Add 2 large eggs, one at a time, beating on medium speed 1 minute after each addition. Mix in ½ cup sour cream and 1 tsp. vanilla extract. Scrape down sides of bowl and beat once more to make sure batter is smooth and homogenous (don’t worry if it looks curdled). Add dry ingredients and beat on low speed until nearly incorporated. Add 2½ cups (325 g) fresh or frozen conventional or wild blueberries and fold into batter with a rubber spatula. The batter will be very thick, especially if you’re using frozen berries. Scrape batter into prepared pan and spread out evenly with spatula (you might have to use some force).
Sprinkle reserved streusel over batter, squeezing the topping between your hands if you want bigger clumps and breaking them up if you want smaller ones.
Bake buckle until streusel is golden brown all over and a tester inserted into the center comes out clean, 55–60 minutes. Transfer pan to a wire rack and let cake cool in pan. Using parchment overhang, hoist buckle out of pan and cut into 9 squares.