Stir together cinnamon and 11/2 teaspoon each of salt and pepper in a bowl, then rub over chops. Broil in a 4-sided sheet pan 3 to 4 inches from heat, turning once, 8 to 10 minutes total for medium-rare.
Meanwhile, make chimichurri and cook peas: With motor running, drop garlic into food processor and finely chop. Add remaining sauce ingredients and 1/2 teaspoon salt and pulse until herbs are finely chopped. Transfer to a bowl.
Cook peas in water and butter in a small saucepan over medium-high heat, covered, stirring once or twice, until just tender, about 3 minutes.
Serve chops drizzled with a little chimichurri and serve peas and remaining chimichurri on the side.