Prepare the Cookie Bars:

Preheat Oven: Preheat your oven to 350°F (175°C). Grease and line a 9x13-inch baking dish with parchment paper, leaving an overhang for easy removal.

Cream the Butter and Sugars: In a large mixing bowl, cream together the softened butter, granulated sugar, and powdered sugar until light and fluffy.

Add Eggs and Extracts: Beat in the eggs one at a time, followed by the vanilla extract and almond extract (if using), mixing until well combined.

Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, and salt.

Mix Together: Gradually add the dry ingredients to the wet mixture, stirring until just combined.

Spread in Baking Dish: Spread the cookie dough evenly in the prepared baking dish.

Bake: Bake in the preheated oven for 25-30 minutes, or until the edges are lightly golden and a toothpick inserted into the center comes out clean.

Cool: Allow the cookie bars to cool completely in the pan on a wire rack. Once cool, lift the bars out using the parchment paper and transfer to a cutting board.

Prepare the Frosting:

Make the Frosting: In a mixing bowl, beat together the softened butter and powdered sugar until well combined. Gradually add milk until you reach your desired frosting consistency. Stir in the vanilla extract.

Optional Coloring: If using food coloring, divide the frosting into bowls and mix in your chosen colors.

Assemble:

Frost the Bars: Spread the frosting evenly over the cooled cookie bars. Decorate with sprinkles as desired.

Cut and Serve: Once frosted, cut into squares or rectangles and serve.