Beat egg white at room temperature in a large bowl until foamy.
Combine chili powder, cumin and garlic powder in a small bowl; stir well and fold into egg white. Add cereal; stir gently to coat pieces evenly. Spread cereal mixture on a baking sheet coated with spray. Bake for 15 minutes, stirring every 5 minutes.
Let Nibbles cool on baking sheet; store in an airtight container.