Blackberry Coffee Cake with Pecan Streusel
2 cups plus 1 Tbs. all-purpose flour
1/2 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. fine sea salt
16 Tbs. (2 sticks) unsalted butter, at room temperature
1 3/4 cups granulated sugar
Finely grated zest of 1 orange
2 eggs, beaten, at room temperature
1 tsp. vanilla extract
1 cup sour cream, at room temperature
1 pint blackberries
2 Tbs. firmly packed light brown sugar
1 tsp. ground cinnamon
For the pecan streusel:
3/4 cup all-purpose flour
1/3 cup firmly packed light brown sugar
6 Tbs. (3/4 stick) unsalted butter, at room temperature
1 cup coarsely chopped pecans
Preheat an oven to 350°F. Lightly butter a 9-by-13-inch baking dish. Dust the pan with a little flour, tapping out the excess.
In a bowl, sift together the 2 cups flour, the baking powder, baking soda and salt. In another bowl, using a handheld mixer, beat together the butter, granulated sugar and orange zest on high speed until light in color and texture, about 3 minutes. Gradually beat in the eggs and then the vanilla. Reduce the speed to low and add the flour mixture in 3 additions, alternating with the sour cream and beginning and ending with the flour, beating until smooth. Stop the mixer and scrape down the sides of the bowl as needed.
In another bowl, combine the blackberries, brown sugar, cinnamon and the 1 Tbs. flour. Spread half of the batter in the prepared pan. Top with the berry mixture, taking care that no berries touch the sides of the pan. Spread the remaining batter over the berries, smoothing the top.
To make the streusel, in a small bowl, combine the flour, brown sugar and butter. Using your fingers, work the ingredients together until just combined, then work in the pecans. Press the mixture together into a ball and then separate it with your fingers into coarse crumbs. Sprinkle the streusel evenly over the cake.
Bake until a toothpick inserted into the center of the cake comes out clean, about 45 minutes. Transfer the pan to a wire rack and let the cake cool in the pan for 15 minutes. Cut the cake into squares and serve. Serves 12.