1. Line a large baking sheet with foil or parchment. In a food processor, pulse popcorn, garlic powder and 1/4 tsp. salt until mixture resembles coarse bread crumbs. Transfer to a shallow bowl. Place flour in a second shallow bowl and egg in a third.
2. Dredge each chicken piece in flour, then in beaten egg, then in popcorn crumbs, turning to coat. Transfer to baking sheet and repeat with remaining chicken. Discard any leftover flour, beaten egg and popcorn crumbs when finished.
3. In a large skillet over medium-high heat, combine oil and butter. When butter has melted, add chicken, working in batches if necessary. Do not crowd skillet. Cook, turning once, until chicken is well-browned on both sides and cooked through, about 8 minutes total. Sprinkle with additional salt, if desired.