I love chimichurri and I love pesto. And although both are similar, with many of the same ingredients, they are definitely not the same.
Chimichurri is found in Argentinian, Paraguayan, and Uruguayan cuisines, and features parsley as the main green ingredient. People from those countries will tell you that cilantro has no place in a true chimichurri recipe. It is used as a marinade as well as a side dressing to grilled meats, and often contains vinegar, which pesto does not.
Pesto, on the other hand, is less strict in its ingredients. I’ve made pesto with the classic basil, but also with spinach or arugula. Pesto also features nuts, like the classic pine nuts, but also pistachios, walnuts, or even macadamia nuts. (There are no nuts in chimichurri.) Pesto often features cheese as well.

So when my garden had an abundance of scallions, I decided I would make a chimichurri/pesto hybrid using whatever ingredients I had in my cupboard. What I came up with was absolutely delicious as both a marinade and side dressing. This time, I tried it on chicken.

1 cup chopped scallions, tightly packed
2 large garlic cloves, coarsely chopped
1/4 salted pistachio nuts, shelled
1 teaspoon salt
1/2 teaspoon black pepper
1/4 cup (plus more) extra virgin olive oil

Place the scallions, garlic, pistachios, salt, and pepper in the bowl of a food processor.
Start the processor and slowly drizzle in the olive oil, until you get the consistency of a loose paste.
How thick you want your pesto is a personal choice. You might need more than 1/4 cup of olive oil.

I used chicken leg quarters, and I brushed them on both sides with the pesto, and let them sit for an hour before baking them in a pre-heated 350° oven. They baked for one hour.
A bad weather day prevented me from finishing them on the grill, but they still came out flavorful, with a crispy skin.

I ate the chicken using the extra pesto as a dipping sauce on the side.

Note: For safety, I take a small amount of the pesto and put it in a separate bowl when I brush it on the meat. I don’t want to have raw chicken contaminating the rest of the pesto I will want to use later to serve on the side!