- 12 tablespoons (1 1/2 sticks) unsalted butter, at room temperature
- 1 cup granulated sugar, plus 2 tablespoons for the topping
- 1/2 cup packed brown sugar
- 2 large eggs
- 2 teaspoons vanilla extract
- 2 cups flour
- 1 teaspoon ground cinnamon, plus more for the topping
- 3/4 teaspoon baking powder
- 1/2 teaspoon kosher salt
Preheat the oven to 350 degrees. Grease a 9-inch-square baking pan with cooking oil spray, then line the bottom with parchment paper.
Combine the butter, the cup of granulated sugar and the brown sugar in the bowl of a stand mixer or handheld electric mixer; beat on medium speed for a few minutes, until lightened and a little fluffy. Stop to scrape down the bowl.
Add the eggs and vanilla extract; beat on medium speed until well incorporated.
Whisk together the flour, teaspoon of cinnamon, baking powder and salt in a separate bowl, then add to the mixer bowl; beat on medium-low speed until well incorporated. The dough will be quite soft.
Transfer to the baking pan, then spread the dough evenly all the way into the corners. Whisk together the remaining 2 tablespoons of granulated sugar with the amount of cinnamon you prefer; we recommend 1/2 to 1 teaspoon. Sprinkle that mixture evenly over the surface. Bake (middle rack) for about 25 minutes, until golden and still slightly soft at the center.
Cool completely (in the pan) before serving or storing. It's best to lift out the slab and slice on a cutting board; discard the parchment before cutting.