Whisk together the all-purpose flour, baking soda, salt, and cinnamon in a medium bowl until well blended.

Beat the softened unsalted butter and brown sugar in a large bowl until light and fluffy, then mix in the maple syrup.

Add the egg and vanilla extract to the mixture, then gradually incorporate the dry mixture until just combined.

Cover the dough with plastic wrap and refrigerate for at least 1 hour.

Preheat the oven to 350°F (175°C) once the dough is chilled.

Using a cookie scoop, place dough balls on baking sheets, spaced 2 inches apart, and bake for 10-12 minutes.

Melt unsalted butter in a saucepan over medium heat until golden brown, then whisk in powdered sugar, milk, and maple syrup for icing.

Dip the tops of cooled cookies in the icing, allowing excess to drip off, and sprinkle with flaky salt or toasted pecans if desired.