Preheat oven to 375F.
Line two baking sheets with parchment paper and set aside.
In a medium bowl whisk together dry ingredients: flour, salt, cocoa powder and baking soda, set aside.
Add white and brown sugar, plus vanilla to a large bowl and set aside.
In a medium skillet set over medium high heat, melt butter for 2 minutes, stir and swirl it around the pan, allowing it to brown. Keep the butter moving so it doesn’t burn. Brown it for about 3 minutes, until it has a dark golden brown color.
Remove the pan from the heat and pour the butter over the sugars, using a whisk start mixing them well for about 1 minute. Add the egg and whisk until well combined, add the egg yolk and whisk for about 30 seconds to 1 minute, until fully combined. The mixture must be smooth and shiny.
Add the flour mixture and using a spatula stir until just combined, about 1 minute. Gently stir in chocolate chips. The batter will be soft and very shiny.
Use about 4 tablespoons of batter to form a cookie ball, flatten it into you hand and place cookies 2 inches apart on the prepared baking sheets. Bake for 10-12 minutes, mid baking switch the sheet trays in the oven: the upper one goes to the bottom, and the bottom one is moved up. The cookies are done when set around the edges, but puffy in the middle. Mine were perfectly baked in 12 minutes.
Allow cookies to cool on the pan for 1 to 2 minutes, and then transfer to a wire rack to cool completely.