1 ½ cups all-purpose flour
1 teaspoon baking powder
½ teaspoon salt
¾ cup unsalted butter, softened
¾ cup light brown sugar, packed
½ cup granulated sugar
2 large eggs
1 teaspoon vanilla extract
¼ cup granulated sugar (for swirl)
1 tablespoon ground cinnamon (for swirl)
Preheat oven to 350°F (175°C). Line an 8×8 inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
In a medium bowl, whisk together the flour, baking powder, and salt.
In a large bowl, cream the softened butter, brown sugar, and 1/2 cup granulated sugar with an electric mixer until light and fluffy.
Beat in the eggs one at a time, then mix in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed just until the flour is incorporated. Do not overmix.
In a small bowl, mix the 1/4 cup granulated sugar and 1 tablespoon of cinnamon for the swirl.
Spread about two-thirds of the blondie batter into the prepared pan. Sprinkle most of the cinnamon sugar mixture evenly over the batter.
Dollop the remaining batter over the top and gently spread it. Swirl the layers together with a knife. Top with the remaining cinnamon sugar.
Bake for 25-30 minutes, until the edges are golden and the center is set but still slightly soft. A toothpick inserted near the center should have a few moist crumbs.
Let the blondies cool completely in the pan on a wire rack before slicing into squares.
