Adjust oven racks to upper and lower-middle positions. Preheat oven 325°.
Line two cookie sheets with parchment paper or use silpats.
Whisk dry ingredients together in a medium bowl.
With electric mixer, or by hand, mix butter and sugars until thoroughly combined.
Beat in egg, yolk, and vanilla until combined.
Add dry ingredients and beat at low-speed just until combined.
Stir in chocolate chips.
Roll 2 tbsp of dough into a ball and place onto cookie sheet, leaving room between each ball. Sprinkle with sea salt. Bake until cookies are light golden brown and outer edges start to harden yet centers are still soft and puffy (approximately 11-14 minutes). Do not over bake, it is too easy to do! Cool cookies on sheets until able to lift without breaking. Transfer to a wire rack to cool. I mean you can eat them immediately but you will burn your tongue on the chocolate chips...I do every time.