Pre-heat oven to 500 degrees. Line a baking sheet with foil and place a cooling rack on top (or use a roasting pan).
Add all chimichurri ingredients to a food processor and pulse until leaves are chopped into about 1/8" pieces (or desired size). Set aside.
Spatchcock chicken, pat it dry and rub it with about 1/2 tbsp olive oil, then generously season with salt and pepper. Top it with 1-2 tbsp chimichurri.
Place spatchcocked chicken on top of cooling rack (or roasting pan) and tuck the wing tips under the bird so they don't burn.
Bake for 30-40 minutes, turning down temperature to 450 degrees if skin is getting dark around the 20-25 minute mark. The chicken is cooked when the middle of the chicken breast reads 165 degrees (and center of thigh reads 180 degrees) and juices run clear.
Top chicken and serve with remaining chimichurri.