Preheat oven to 375 F. Line a cookie sheet with parchment paper or silplat mat.
Dry ingredients: flour, cocoa powder, baking powder, baking soda and salt in medium bowl; set aside.
Wet ingredients: butter, sugar and brown sugar in a separate mixing bowl and beat for a few minutes until creamed together. Add egg and vanilla and mix until combined.
Combine: Gradually mix in the flour mixture until combined. Stir in chocolate chips.
Refrigerate: Cover bowl and refrigerate dough for 30 minutes (or up to 3 days stored in an air-tight container).
Scoop dough using a1/4 cup measuring cup to make them uniform in size. Place on a baking sheet 2 inches apart.
Bake for 12 to 15 minutes or until set around the edges (don't over bake!). Allow to cool for several minutes on the baking sheet before transferring to a wire rack to cool completely
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Notes
Make Ahead Instructions: The cookie dough can be made up to 3 days ahead of time, stored in an air-tight container in the fridge.Freezing Instructions: Freeze cookie dough for up to 3 months. To freeze baked cookies, allow them to cool completely and freeze in a freezer safe container for up to 3 months.