Preheat oven to 325F and line an 8x8 metal baking pan with parchment paper leaving the sides high.

In a medium bowl whisk together all-purpose flour, sea salt and baking powder.

Using a stand mixer or large bowl, mix sugars and butter on low speed to combine.

Add in egg, pure vanilla and mix again on low (about 30 seconds), stopping to scrape down the sides as needed. Add in chopped chocolate and mix until combined.

Mix cinnamon sugar topping in a small bowl and sprinkle over top.

Transfer cookie dough into 8x8 pan and flatten with an offset spatula.

Bake for 30 minutes or until the edges look set; a toothpick comes out of the center with moist crumbs.