Start by preheating the oven to 350F then line a large baking sheet with parchment paper or a silicone baking mat.
In a small bowl, mix together the flour, cocoa powder, baking powder and salt. Set aside.
In a small saucepan melt the butter over medium-low heat. Remove the pan from the heat and add in the chocolate chips. Stir until melted and well incorporated.
While the butter and chocolate mixture in melting, whisk the room temperature egg and both the granulated sugar and brown sugar using a stand mixer or a hand mixer. Beat on medium-high speed for 3-5 minutes or until the mixture is light and airy.
Slowly add in the chocolate mixture into the egg mixture and gently fold. Add in the dry ingredients to the wet mixture again and fold using a rubber spatula. Avoid over-mixing, you want to fold in the dry i=mixture just until it's combined.
Using a small cookie scoop, drop the batter in balls onto the parchment lined baking sheet, leaving about 2 inches in between each cookie. Top the cookie dough with sea salt if you want and bake for 10 minutes.
Remove the cookies from the oven and let them cool for 10-15 minutes on the baking sheet before transferring to a cooling wrack to cool completely!
These cookies will last up to 6 days in an airtight container in the fridge or for 3 months in an airtight container in the freezer.