Preheat oven to 350°F. Line 2 large baking sheets with parchment paper. Set aside.
In a medium bowl, whisk together the flour, baking soda, and kosher salt. Set aside.
To the bowl of a stand mixer fitted with the paddle attachment, add the butter and brown sugar. Mix on medium speed until smooth and creamy, about 1-2 minutes.
Add the egg and mix until combined.
Add the maple syrup, vanilla extract, and maple extract. Beat on high speed until well combined, scraping down the sides of the bowl as needed.
Add the flour mixture to the wet ingredients. Mix on low speed until just combined.
Use a 2-tablespoon cookie scoop to scoop out portions of dough. Roll the dough into balls and place them on the baking sheets about 2 inches apart.
Bake for 8-9 minutes, or until golden brown on the edges, but still slightly doughy in the center.
Let the cookies cool for 5 minutes before transferring to a wire rack to cool completely. While the cookies are cooling, make the glaze.
In a medium bowl, combine the confectioners' sugar, maple syrup, melted butter, maple extract, and a pinch of kosher salt. Mix well to combine until smooth.
Once the cookies are completely cool, drizzle the maple glaze over the tops.