In a large bowl, whisk together the flour, baking soda and salt. Set aside.
In the bowl of a stand mixer (or using a hand mixer), beat butter and brown sugar until light and fluffy, about 3 minutes. Add egg and egg yolk, and mix until well combined. Scrape down the bottoms and sides of the bowl as necessary. Add maple syrup, vanilla and maple extract. Mix until well combined.
Add the flour and mix just until combined, then stir in the pecans by hand.
Cover and chill the dough for at least 2 hours.
Preheat the oven to 350° F. Line a baking sheet with parchment paper.
Using a medium cookie scoop, scoop cookie dough and roll into balls (as an option, roll the cookie dough balls in crushed pecans for extra crunch) Place on prepared baking sheet about 2 inches apart and bake for 12 minutes. Allow cookies to cool on the pan for a few minutes before transferring to a wire rack to cool completely.
For the glaze, whisk together the confectioners sugar, maple syrup, vanilla and milk. Drizzle over cookies and serve.
Maple syrup: Grade B pure maple syrup is best for these cookies, but you can also use Grade A. Do not use pancake syrup.Chill the dough otherwise the cookies will spread and be thin.Store cookies in an airtight container for up to 5 days.Freeze cookie dough for up to 3 months.