Preheat the oven to 350 F and line an 8x8inch pan with parchment paper and set it aside.
In a large bowl, add the butter, brown sugar, and granulated sugar and cream them together for a couple of minutes. 1 cup Unsalted Butter, 1/2 cup Brown Sugar, 1/2 cup Granulated Sugar
Add in the egg, and vanilla extract, and stir them into the mixture. 1 large Egg, 2 tsp Vanilla Extract,
Add in the flour, baking powder and salt and mix it together until you have a soft cookie dough. 2 1/2 cups All Purpose Flour, 1/2 tsp Baking Powder, 1/2 tsp Salt
Take a little more than 1/2 of the cookie dough and press it evenly into the bottom the prepared pan.
Bake the cookie dough for about 10 to 12 minutes or until the top is set and no longer shiny.