This cake is lightly sweet and fluffy but what really makes this cake extraordinary is the sheer amount of golden, sweet crumb topping.  So you can enjoy bite after bite after bite.

Ingredients

Crumb Topping:

• 1/3 cup granulated sugar (2 2/3 ounces)
• 1/3 cup dark brown sugar (2 2/3 ounces)
• 3/4 teaspoon ground cinnamon
• 1/8 teaspoon salt
• 8 tablespoons butter (1 stick), melted and still warm
• 1 3/4 cups cake flour (7 ounces)

Cake:

• 1 1/4 cups cake flour (5 ounces)
• *1/2 cup granulated sugar (3 1/2 ounces)
• 1/4 teaspoon baking soda
• 1/4 teaspoon salt
• 6 tablespoons butter (3/4 stick), cut into 6 pieces, softened but still cool
• 1 large egg
• 1 large egg yolk
• 1 teaspoon vanilla extract
• 1/3 cup buttermilk
• Confectioners’ sugar for dusting (optional)

Directions

For the topping, in a medium bowl, combine the sugars, cinnamon, salt and melted butter. Add the flour and stir with a rubber spatula or wooden spoon until the mixture is thick and smooth. Set aside to cool to room temperature, 10 to 15 minutes.

For the cake, adjust an oven rack to upper-middle position and preheat the oven to 325 degrees F. Cut a 16-inch length parchment paper or aluminum foil and fold lengthwise to 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; allowing the excess to hang over the edges.

In a large bowl (or the bowl of an electric mixer), mix the flour, sugar, baking soda, and salt. With the mixer running at low speed (electric or handheld), add the softened butter one piece at a time and continue beating until the mixture resembles moist crumbs, with no visible butter chunks remaining, 1 to 2 minutes. Add the egg, egg yolk, vanilla, and buttermilk and beat on medium-high speed until light and fluffy, about 1 minute, scraping once if necessary.

Scrape the batter into the baking pan, spreading it into an even layer. Break apart the crumb topping that was set aside into large pea-sized pieces and spread the topping in an even layer over the batter. Bake the cake until the crumbs are golden and a toothpick inserted into the center of the cake comes out clean, 35 to 40 minutes. Cool on a wire rack at least 30 minutes. Remove the cake from the pan by lifting the parchment or foil overhang.  Dust with confectioners’ sugar, if desired, just before serving.

* If you don’t have cake flour on hand you can use a substitution of cornstarch and all-purpose flour. Measure 2 tablespoons cornstarch into a 1-cup measure and fill the rest of the way with all-purpose flour. That ends up being 7/8 cup all-purpose flour and 1/8 cup cornstarch. Then sift the mixture through a fine-mesh strainer onto a piece of waxed paper (repeating as necessary depending on how much you need – for this recipe there is a total of 3 cups of cake flour).   Also, the recipe can also be doubled and baked in a 9X13-inch baking dish (increasing the baking time to about 42 minutes).

Recipe from Cook’s Illustrated