Potato-Cheddar Frittata

Directions

1. Preheat broiler. In a large bowl, whisk the first 8 ingredients. In a 10-in. cast-iron or other ovenproof skillet, heat oil over medium-high heat. Add potatoes with onion; cook and stir until tender, 3-4 minutes. Reduce heat; pour in egg mixture. Cook, covered, until nearly set, 5-7 minutes.
2. Broil 3-4 in. from heat until eggs are completely set, 2-3 minutes. Let stand 5 minutes. Cut into wedges.