Preheat the oven to 350°. Spread the pecans on a large rimmed baking sheet and toast until they are fragrant, about 10 minutes. Let the pecans cool. Lower the oven temperature to 250°.
Line 2 baking sheets with parchment paper. In a large bowl, toss the pecans with the maple syrup, butter, salt, cayenne and black pepper. In a medium bowl, whisk the egg white until frothy. Add the egg white to the pecans and toss well.
Spread the pecans on the lined baking sheets in a single layer. Bake for 40 minutes, until the nuts are golden brown. Immediately loosen the pecans from the paper with a spatula. Let cool completely on the baking sheets before serving.
The nuts can be stored in an airtight container for up to 1 week.