Mix the cumin, chili powder, cinnamon, and cayenne in a small bowl and set aside.

Preheat a large cast-iron skillet or other large skillet over medium heat.

Add nuts and toast until slightly browned, being careful not to burn.

Add butter and vanilla to coat nuts, then sprinkle spice mixture over nuts and stir until well combined.

Spread nuts out on large cookie sheet to dry, or serve warm right out of the pan.