Preheat Your Oven: Begin by preheating your oven to 350°F (175°C). Don’t forget this critical step—nobody likes underbaked cookie bars!
Mix the Wet Ingredients: In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. This should take about 2-3 minutes. Next, add the eggs one at a time, beating well after each addition, and stir in the vanilla extract.
Combine Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add the dry mixture to the wet mixture, mixing just until incorporated.
Spread the Dough: Grease a 9x13 inch baking pan or line it with parchment paper for easy removal. Spread the cookie dough evenly in the pan.
Bake: Bake in the preheated oven for 20-25 minutes or until the edges are lightly golden. A toothpick inserted in the center should come out clean.
Cool and Frost: Allow the cookie bars to cool completely in the pan. Once cooled, top with your choice of frosting and add any desired toppings like sprinkles.
Slice and Serve: Cut into squares or rectangles for easy serving and enjoy!
