Preheat the oven to 425°F (220°C).
In a small bowl, whisk together olive oil, minced garlic, lemon zest, lemon juice, dried oregano, salt, black pepper, and red pepper flakes to create the marinade.
Place the chicken thighs in a large bowl or baking dish and pour the marinade over them. Toss to coat the chicken evenly.
Arrange the chicken thighs skin-side up in a single layer in a baking dish or on a rimmed baking sheet.
Bake in the preheated oven for 35 minutes, or until the chicken is cooked through and the skin is crispy. The internal temperature should reach 165°F (74°C).
Remove from the oven and let rest for 5 minutes.
Sprinkle chopped fresh parsley over the chicken thighs before serving.