In a bowl, stir together flour, baking soda and salt. Set aside.
In a mixing bowl, beat butter on medium speed until mayonnaise consistency, about 1 minute.
Add sugars and maple syrup, beat for 1 minutes on medium speed, scrape down sides, then beat for 1 more minutes so the mixture is light and fluffy. It's important to beat it for a total of 2 minutes. Add egg and yolk, and vanilla extract, incorporate on low speed for 20 seconds.
Then incorporate flour mixture in 2 additions, until batter comes together and no flour streaks are present. Stir in chocolate with spoon. Cover dough and refrigerate for ideally 4-6 hours (or overnight). Will still work if you only refrigerate for 2 hours, they will just be a bit flatter and less flavorful.
After dough has chilled, make cookie dough balls that are a scant 2 tablespoons of batter (about 60 grams), putting 6 cookies on a parchment lined baking sheet. Preheat oven to 350 degrees F. Bake for 12-14 minutes, until edges are just golden brown. They should look a little under-baked in the middle, starting to brown on the outside. Remove from oven and let cool on pan for 5 minutes, then move to cooling rack.