Preheat the oven to 350°F. Position two racks near the center and line two baking sheets with parchment paper.

In a medium bowl, whisk together the flour, cornstarch, baking soda, salt, cinnamon, and cream of tartar. Set aside.

In a large bowl, using a hand mixer or a stand mixer with the paddle attachment, beat the butter, brown sugar, and granulated sugar until light and creamy, about 2 minutes. Add the maple syrup, egg, and maple extract, beating until combined. Scrape down the sides and bottom of the bowl. Gradually add the flour mixture and beat just until incorporated. Fold in the chopped pecans.

In a shallow bowl, stir together the granulated sugar and cinnamon for the coating.

Using a 3-tablespoon cookie scoop, portion the dough into balls. Roll each ball in the cinnamon sugar mixture and place them 2 inches apart on the prepared baking sheets. Keep the dough balls round rather than flattened to ensure thick cookies.

Bake for 11 to 13 minutes, until the edges are set but the centers still look slightly underdone. The cookies will be very soft and should not be moved immediately. Let them cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.