Preheat oven to 375°F. Line 2 baking sheets with parchment paper, set aside.
In the bowl of a stand mixer, fitted with the paddle attachment, add butter, granulated sugar, brown sugar, maple syrup, vanilla extract and maple extract. Beat on medium speed for 8 minutes. Yes, 8. Read in the post for why we do this.
Turn mixer off, add egg and egg yolk one at a time, mixing on low speed until dough is smooth.
In a medium bowl, mix together flour, baking soda and salt.
Add flour mixture to butter mixture all at once. Mix on low just until flour is blended, not a second more. This takes my Kitchen Aid mixer about 10 times around the bowl.
Add chocolate chips and mix for about 3 seconds, until evenly distributed.
Using a 3 tablespoon scoop, place dough balls 2 inches apart on baking sheets. Bake on center rack for 10-12 minutes, until lightly brown on the edges and still soft in the center.
Allow to cool on baking sheet for 2-3 minutes, then transfer to cooling rack. Sprinkle kosher salt while warm if you like that extra saltiness.