Preheat oven to 350°F (177°C) and line a cookie sheet with parchment paper.
In a medium sized mixing bowl, sift together the all-purpose flour, baking powder, baking soda, and salt. Set aside.
In a separate mixing bowl, using either a hand mixer or a stand mixer, cream together the unsalted room temperature butter and brown sugar.
Add the vanilla extract and egg to the bowl, then beat the mixture until it becomes creamy and well combined, which should take about a minute.
Gradually add the dry ingredients into the bowl with the wet ingredients, mixing until your cookie dough forms.
Gently fold in the chopped Heath bar pieces until they are evenly distributed throughout.
Scoop the cookie dough into 3 tablespoon portions, and place the cookies on a parchment lined baking sheet and space them 3 inches apart.
Bake on the center rack of your preheated oven for 10-12 minutes.
Once you remove the cookies from the oven, let them cool for at least 10 minutes before transferring them to a cooling rack to finish cooling.
