This recipe is from Cooks Illustrated May 2007 issue (no link available). Photo from Ourbestbites.com
- Crumb Topping
- 1/3 cup white sugar
- 1/3 cup dark brown sugar
- 3/4 teaspoon ground cinnamon
- 1/8 teaspoon table salt (omit if using salted butter)
- 8 tablespoons (1 stick) butter, melted and still warm
- 1 3/4 cups cake flour (7 ounces if you have a kitchen scale)
- 1 1/4 cups cake flour (5 ounces)
- 1/2 cup white sugar
- 1/4 teaspoon baking soda
- 1/4 teaspoon table salt (omit if using salted butter)
- 6 tablespoons (3/4 stick) butter, cut into 6 pieces, softened but still cool
- 1 large egg
- 1 large egg yolk
- 1 teaspoon vanilla extract
- 1/3 cup buttermilk
- Powdered sugar for dusting (optional)
For the topping, whisk sugars, cinnamon, salt, and butter in medium bowl. Add flour and stir with rubber spatula or wooden spoon until the mixture is thick like cookie dough. Set aside to cool to room temperature, 10 to 15 minutes.
For the cake, adjust oven rack to upper-middle position and heat oven to 325 degrees. Spray an 8×8″ baking dish with non-stick cooking spray. Set aside.
In bowl of standing mixer fitted with paddle attachment, mix flour, sugar, baking soda, and salt (if using) on low speed to combine. With mixer running at low speed, add butter one piece at a time; continue beating until mixture resembles moist crumbs, with no visible butter chunks remaining, 1 to 2 minutes. Add egg, yolk, vanilla, and buttermilk; beat on medium-high speed until light and fluffy, about 1 minute, scraping once if necessary.
Transfer batter to baking pan; using rubber spatula, spread batter into even layer. Spread the topping in an even layer starting at the edges and ending in the middle. Bake until crumbs are golden and wooden skewer inserted into center of cake comes out clean, 35 to 40 minutes. Cool on wire rack at least 30 minutes. If desired, dust the cake with powdered sugar before serving.