This amazing chicken dish is from Bon Appetite. The olive mixture would be amazing on pasta as well.
10 oil-packed anchovy fillets
4 garlic cloves
1½ c green olives (such as Castelvetrano), plus ½ c brine reserved
½ c olive oil
1 TBSP lemon zest
2 TBSP lemon juice
Salt and pepper
1 small onion, thinly sliced
½ c coarsely chopped fresh oregano
1 3½–4-pound chicken, halved lengthwise
Toss anchovies, garlic, olive brine, olive oil, and lemon juice in a food processor, pulse until finely chopped; season with salt and pepper. Place half of anchovy mixture in a large resealable plastic bag; add onion and chopped oregano. Add the lemon zest and oloves to the food processor and pulse until finely chopped. Cover and chill remaining anchovy mixture.
Season chicken with salt and pepper and add to bag, seal bag, and toss to coat. Let marinate 4–12 hours.
Prepare grill for medium heat; generously oil grate with vegetable oil. Remove chicken from marinade, letting excess drip back into bag (a few pieces of onion and oregano still clinging are okay); discard marinade. Starting skin side up, grill chicken, turning occasionally, until lightly charred and cooked through, 30–40 minutes.
Meanwhile, set out reserved anchovy mixture and let come to room temperature.
Place chicken on a plate and spoon anchovy-olive mixture around.