First, preheat your oven to 400F. Then, pat chicken thighs completely dry with paper towels, ensuring little to no moisture is left. Once, dry, season liberally all over with salt and pepper. Once seasoned, take a medium bowl and mix together the butter, garlic, lemon zest, and them. Spread the butter mixture onto the thighs, ensuring that you get under the skin as well. Place the lemon rounds and baby potatoes in an even layer of a 9x13 baking dish, placing the chicken thighs in a layer on top. Bake for about 35-40 minutes, or until the thighs reach an internal temperature of 160F. Remove from oven and garnish with fresh chopped parsley.