Preheat the oven to 325 degrees F. Line a baking sheet or two with parchment paper.

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

In the bowl of your electric mixer, beat the butter and sugars until combined and fluffy, about 5 minutes. Beat in the egg and egg yolk until just combined. Beat in the vanilla extract. With the mixer on low speed, beat in the dry ingredients until just combined. Beat in the chopped chocolate.

Use an ice cream scoop or a spoon, scoop or drop 1 1/2 to 2 tablespoons of dough on to the baking sheet, leaving about 2 inches between. Sprinkle each dough ball with coarse salt.

Bake for 12 to 15 minutes, until set in the center and slightly golden. Let cool completely – these are amazingly chewy once cooled!