New York-Style Crumb Cake

Ingredients

• Crumb Topping:
• 1/3 cup granulated sugar
• 1/3 cup dark brown sugar
• ¾ teaspoon ground cinnamon
• 1/8 teaspoon salt
• 8 tablespoons unsalted butter, melted and still warm
• 1 ¾ cups cake flour
• Cake:
• 1 ¼ cups cake flour
• ½ cup granulated sugar
• ¼ teaspoon baking soda
• ¼ teaspoon salt
• 6 tablespoons unsalted butter, cut into 6 pieces, softened but still cool
• 1 large egg plus 1 large yolk
• 1 teaspoon vanilla extract
• 1/3 cup buttermilk
• Confectioners’ sugar, for dusting

Directions

1. For the topping: Whisk sugars, cinnamon, salt, and butter in a medium bowl to combine. Add flour and stir with a rubber spatula or wooden spoon until the mixture resembles a thick, cohesive dough; set aside to cool to room temperature for 10-15 minutes.
2. For the cake: Adjust oven rack to upper-middle position and heat oven to 325 degrees. Cut a 16-inch length of parchment paper or aluminum foil and fold lengthwise to a 7-inch width. Spray an 8-inch square baking dish with nonstick cooking spray and fit the parchment into the dish, pushing it into the corners and up the sides; allow excess to overhang the edges of the dish.
3. In the bowl of a standing mixer fitted with the paddle attachment, mix flour, sugar, baking soda, and salt on low speed to combine. With the mixer running at low speed, add butter one piece at a time; continue beating until the 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.
4. Transfer batter to the baking pan using a rubber spatula and spread into an even layer. Break apart the crumb topping into large pea-sized pieces and spread in an even layer over the batter, beginning with the edges and then working toward the center.
5. Bake until crumbs are golden and a wooden skewer inserted into the center of the cake comes out clean, 35-40 minutes. Cool on a wire rack at least 30 minutes. Remove cake from pan by lifting the parchment overhang. Dust with confectioners’ sugar just before serving.