Blueberry Buckle

This is a very dense coffee cake, a few shades away from a blueberry pie. Fresh blueberries are essential (frozen will bleed all over and make it inky), which means you should have about eight blueberry bushes in your yard.

For the streusel:

1/2 cup unbleached all-purpose flour
1/2 cup light brown sugar, packed
2 tbs. granulated sugar
1/4 tsp. ground cinnamon
pinch of salt
4 tbs. cold butter in 8 pieces

In a standing mixer with paddle beater, combine flour, sugars, cinnamon and salt and mix until no brown sugar lumps remain. Add butter and mix until you achieve a mixture like coarse, wet sand, with no visible butter lumps. This is the streusel topping. Put it into a small bowl and set it aside.

For the buckle:

1 1/2 cups all-purpose flour
1 1/2 tsp. baking powder
10 tbs. unsalted butter
2/3 cup granulated sugar
1/2 tsp. salt
grated zest of one lemon
1 1/2 tsp. vanilla extract
2 large eggs at room temperature
4 cups fresh blueberries, cleaned

Preheat oven to 350 degrees. Spray a 9-inch round cake pan with cooking spray or thoroughly butter it. Cut a baking parchment circle to fit the bottom, insert it in the pan and spray the parchment again. Dust pan with flour and shake out excess.

Whisk flour and baking powder in a small bowl and set aside. Using the stand mixer with paddle beater, cream the butter, sugar, salt, and lemon zest until light and fluffy, about 3 minutes, scraping the bowl as necessary. Beat in vanilla.

With mixer running, add eggs one at a time. Mixture will appear broken. Gradually add flour mixture until almost incorporated. This should take no more than 20 seconds. Do not overbeat. Take the bowl out of the mixer, scrape the sides, and finish by hand if necessary to incorporate any remaining flour.

The batter will be as stiff as cookie dough. Using a rubber spatula, gently fold in the blueberries, then pack the mixture into the prepared pan, using the spatula to spread it evenly. Grab a handful of streusel, squeeze it into a lump, then break off raisin-size bits and scatter them evenly over the top. Use all the streusel.

Bake until the buckle is deep golden brown, about 55 minutes or until a toothpick or wooden skewer stuck into the middle comes out clean (or at least crumbless; it will probably be stained blue). Cool on a rack for 20 minutes. Run a knife around the edge to loosen, then invert onto a plate. Remove the parchment circle, then invert onto the serving plate. Cool to lukewarm (it will take the blueberries a while to reach the lukewarm stage), cut and serve.