Place Unsalted Butter (1 cup) in a saucepan and set over low heat, until just half is melted. Cool for 5 minutes, while you prepare the dry ingredients.
In a medium bowl, whisk together sifted Pastry Flour (2 1/2 cup), Salt (1/2 teaspoon), and Baking Soda (1/2 teaspoon). Make sure to sift the flour before measuring.
Pour butter into a large bowl. Add Dark Brown Sugar (1 cup) and Maple Sugar (1 cup) and whisk until combined. Whisk in Egg (2), one at a time.
Then whisk in the Maple Extract (1 teaspoon). Dough will be goopy.
Add dries, one third at a time, to wets, mixing with a rubber spatula or wooden spoon. Wrap bowl with plastic wrap and chill for at least 20 minutes.
Preheat oven to 325 degrees F (160 degrees C) with racks in upper and lower thirds. Line two half-sheet baking pans with parchment paper.
Form dough into balls about the size of whole walnuts and place 2 inches apart on prepared baking sheets. Bake for 12 to 14 minutes, or until edges are light brown and centers are still wet—don’t overbake.
Immediately transfer cookies to a cooling rack. Cool for 1 hour before serving.