Preheat your oven to 350.

You will need to line your baking sheets with parchment paper. 

In a medium bowl, sift together the flour, baking soda, and salt. 

In the bowl of a stand mixer (or a medium bowl if using a handheld mixer), mix the butter and both sugars on low speed until well combined and creamy. Add in the egg, the yolk, and vanilla. Mix well. Turn off the mixer and add about 1/3 of the flour mixture. Turn the mixer back on low speed, mix until the flour is incorporated, repeating until all the flour is combined into the batter. Then, return to low speed and add the chocolate chips. Once the chocolate chips are stirred throughout, turn the mixer off and find your favorite small scooper, or get two soup spoons. I prefer the scooper. Otherwise, use your two spoons to scoop out batter and shape it into even portions. 

Place portioned cookie dough onto your baking sheet(s), about 2 inches apart. Sprinkle the tops with the Maldon sea salt flakes, as much as you wish. 

Bake for about 13-15 minutes. I usually go for 15. 

When you remove the pan from the oven, sort of slam it on your counter. This promotes extra air to be expelled and lends to a crispier exterior.