Heat oven to 350℉/177℃.
Line sheet pans with parchment paper.
Pour maple syrup into a small saucepan, like a butter warmer, or in a 1½-2 cup microwave safe bowl.
Cook maple syrup over low heat on the stove, or in short bursts in the microwave, until it is thick and reduced by at least half. (Be careful! The maple syrup bubbles up!) Set aside.
In a medium bowl, whisk granulated sugar, brown sugar, maple syrup, salt, and butter together.
Whisk in the egg and vanilla.
Add flour and baking soda.
Stir until combined.
Fold in pecans.
Use a 3 Tablespoon scoop to portion dough onto prepared pans. (We did 4 cookies per 12-inch x 18-inch pan.)
Bake for 12 minutes, until just starting to color on the edges.