Preheat the oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
In a large bowl, beat the 1 cup softened butter and granulated sugar together with an electric mixer on medium speed until light and fluffy, about 3-4 minutes.
Add the egg, vanilla extract, and almond extract to the butter mixture and beat until combined.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Press the cookie dough evenly into the prepared baking pan.
Bake for 22-25 minutes, or until the edges are lightly golden and a toothpick inserted into the center comes out clean.
Remove from the oven and allow the cookie bars to cool completely in the pan on a wire rack.
While the bars cool, prepare the frosting by beating together the powdered sugar, 2 tablespoons softened butter, milk, and vanilla extract until smooth and creamy.
Spread the frosting evenly over the cooled cookie bars.
Decorate the top with red, white, and blue sprinkles to create a festive 4th of July look.
Use the parchment paper overhang to lift the bars out of the pan. Cut into 16 squares and serve.