Line a cookie tray with parchment paper.
Melt butter in large skillet over medium heat.
Stir in maple syrup, vanilla, and spices.
Bring to a simmer (mixture should be frothy), about 3 minutes.
Add pecans and toss to coat using a rubber spatula.
Cook, stirring, until sauce is reduced and bubbly, about 3 minutes.
Transfer the mixture to the lined cookie sheet and spread into a single layer.
Bake at 375°F until the pecans are caramelized, about 10 minutes.