- 1 cup firmly packed dark brown sugar
- ½ cup granulated sugar
- 1½ teaspoon salt
- 1½ tablespoons cinnamon
- 1 cup (2 sticks) unsalted butter, melted and warm
- 2½ cups all purpose flour
- 2½ cups all purpose flour
- ¾ teaspoon baking powder
- 1 teaspoon baking soda
- ½ teaspoon salt
- 12 tablespoons (1½ sticks) unsalted butter
- 1½ cups granulated sugar
- 2 large eggs
- 1¼ cups sour cream
- 1 teaspoon pure vanilla extract
- Preheat the oven to 350 degrees F and position the rack in the center. Butter the sides and bottom of a glass 9-by-13-inch pan. You can use a metal pan, but the edges of the cake may turn crispy (although that is not traditional, it is not an altogether bad thing).
- To make the crumb topping:
- In a medium bowl, stir together both sugars, the salt, and cinnamon. Add the melted butter and whisk until combined. Fold in the flour until it is absorbed and set the mixture aside.
- To make the cake:
- Sift the flour, baking powder, baking soda, and salt together in a medium bowl. Set aside.
- In the bowl of a standing mixer fitted with the paddle attachment, cream the butter until it is completely smooth and ribbonlike. Serape down the bowl and add the sugar. Beat the mixture until it starts to look fluffy.
- Add the eggs, one at a time, and beat until incorporated. Scrape down the sides of the bowl and mix again for 30 seconds. Add the sour cream and vanilla and beat just until incorporated. Add the dry ingredients in three parts, scraping down the bowl before each addition, beating only until it is just incorporated.
- To assemble the cake:
- Pour the batter into the prepared pan. Use your hands to scoop up a handful of the topping and make a fist. The topping should hold together. Break off in chunks and drop them over the cake. Repeat to use all the topping. Remember, the topping layer will look outrageously thick.
- Bake the cake for 45 to 65 minutes, or until a toothpick inserted in the middle comes out clean. Rotate the pan two times during the baking process. Cool the entire pan on a wire rack for about 30 minutes before serving.
- The cake will last for 3 days, tightly covered, at room temperature.