In a small dish, combine the seasonings. Generously season both sides of the chicken thighs with the seasonings.
Cook the chicken:
Heat a large pan over medium-high heat. Once hot, heat the oil (or melt the butter). Place the chicken thighs on the pan and cook the first side for 7 minutes, until the bottoms are golden and they easily lift to flip them over. There should be some room between the chicken pieces. If not, cook in two batches.
Flip and cook the other side for another 7 minutes until the internal temperature at the thickest part reaches 175F. Cooking time on the second side can vary and might need an additional 2 minutes if the thighs are really thick. Remove onto a plate and cook additional chicken if necessary.
Make the chimichurri:
While the chicken cooks, place the garlic in a food processor, and pulse several times until chopped. Add the Italian parsley (thin stems are fine), and pulse again. Add the oil, lemon juice, cumin, and salt. Pulse until combined.
Transfer the chimichurri to an airtight container or glass jar and refrigerate for up to one week.
Serve:
Serve the chicken thighs topped with chimichurri sauce over the top.