Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper for easy cleanup.
In a large mixing bowl, combine the melted butter, maple syrup, cinnamon, salt, nutmeg (if using), and vanilla extract. Whisk together until smooth.
Add the pecan halves to the bowl and stir gently until they are evenly coated with the syrup mixture.
Spread the coated pecans in a single layer on the prepared baking sheet.
Roast in the preheated oven for 15-20 minutes, stirring halfway through, until the pecans are golden brown and fragrant. Keep a close eye towards the end to prevent burning.
Once roasted, remove from the oven and allow to cool completely on the baking sheet; the pecans will harden as they cool.
Once cooled, break apart any clustered pecans and store them in an airtight container.
Notes
Keep an eye on the pecans while roasting to prevent burning.