- 2 cups all-purpose flour, plus more for the pan (250g)
- 5 1/2 tablespoons (1/3 cup) unsalted butter (75g)
- 1/2 cup granulated sugar (100g)
- 1 large egg, at room temperature
- 1/4 cup sour cream, at room temperature (60g)
- 2/3 cup milk, at room temperature (160g)
- 1 tablespoon vanilla extract (15g)
- 1 tablespoon baking powder (12g)
- pinch of kosher salt
- 2 1/4 cups all-purpose flour (280g)
- 1 1/4 cups packed light brown sugar (290g)
- 1 tablespoon ground cinnamon (6g)
- 1/2 pound (2 sticks) unsalted butter, melted (226g)
- powdered sugar, for dusting
- Place the rack in the center of the oven. Preheat the oven to 350ºF. Spray a 9×13-inch glass baking pan with cooking spray, then dust with flour. Tap out the excess.
- In a mixer with the paddle attachment, beat the butter and sugar until light and fluffy. Add in the egg and sour cream and mix until combined.
- In a small bowl or measuring cup, combine the milk and the vanilla. In another bowl, whisk together the 2 cups flour and the baking powder. Add in the salt.
- Turn the mixer on low speed and alternately add the wet ingredients and the dry ingredients, starting and finishing with the dry ingredients, stopping to scrape down the sides of the bowl several times..