In a bowl, stir together flour, baking soda and salt. Set aside. In another bowl, stir together sugars and maple syrup so that no lumps remain. Set aside.
In a mixing bowl, beat butter on medium speed until mayonnaise consistency, about 1 1/2 minutes.
Add sugar mixture and beat for 1 1/2 minutes on medium speed, scrape down sides, then beat for another 1 1/2 minutes so the mixture is light and fluffy. Add egg and walnut extract, incorporate on low speed for 20 seconds.
Then incorporate flour mixture in 3 additions, until batter just comes together and no flour streaks are present. Stir in chocolate with spoon. Refrigerate for 30 minutes. Meanwhile, preheat oven to 350 degrees. After batter has chilled, make cookie dough balls that are a scant 2 tablespoons of batter. Bake 8 cookies per sheet for about 12 minutes.
They should look a little underbaked in the middle, starting to brown on the outside.