Step 1

Set a large piece of foil and a heavy skillet aside for weighing down chicken. Season chicken on both sides with salt and pepper. Pour 1 Tbsp. oil into a medium cast-iron skillet. Arrange chicken thighs in pan skin side down (make sure they don’t overlap) and set pan over medium-high. Place foil over chicken, then set skillet on top. Cook chicken, checking halfway through to make sure skin isn’t taking on color too quickly and reducing heat to medium if needed, until skin is deep golden brown and crisp and flesh is almost completely cooked through, about 10 minutes.

Step 2

Meanwhile, combine anchovy, garlic, parsley, and a pinch of salt in a small bowl. Mix in vinegar, mustard, red pepper flakes, and remaining 4 Tbsp. oil, then scallions. Taste and season pesto verde with more salt if needed.

Step 3

Remove top skillet and check chicken. There should be only a thin band of medium-rare flesh on the thickest part of thighs. Using a thin spatula, release chicken skin from pan and turn thighs over. Remove pan from heat and let chicken sit to finish cooking through, about 1 minute.

Step 4

Spoon some pesto verde onto a platter. Top with chicken, arranging skin side up, and spoon more pesto over (but don’t cover up all that beautiful skin!).