Festive red, white, and blue blondie cookie bars are a fun patriotic dessert. They have classic buttery brown sugar vanilla flavor with a gooey cookie texture. And you can customize the sprinkle colors for any occasion!
Prep. Preheat the oven to 350F. Line an 8 by 8-inch baking pan with 2 sheets of parchment paper so it hangs over all 4 sides.
Make the batter. Whisk together the warm melted butter, granulated white sugar, and brown sugar in a large bowl. Whisk in the egg, vanilla extract, and vanilla bean paste. Add the flour and salt, and whisk to combine, being careful not to over-mix. Stir in 5 tablespoons sprinkles and the white chocolate.
Bake. Transfer the batter to the prepared baking pan and sprinkle the remaining 1 tablespoon sprinkles on top. Bake until the blondies puff up and are light golden along the outside, about 22 to 25 minutes, being careful not to over-bake.
Cool. Let the blondies cool completely in the pan before removing and cutting. (TIP: If desired, once they're cool, you can drizzle on a little bit of melted white chocolate and top with a few more sprinkles.)
Notes
Storage: Store leftover blondies in an airtight container at room temperature for up to 5 days.