In a large bowl, whisk together olive oil, lemon juice, minced garlic, oregano, salt, black pepper, paprika, and red pepper flakes until well combined.
Add the chicken thighs to the marinade, ensuring they are well coated. Cover and refrigerate for at least 1 hour, or up to overnight for more flavor.
Preheat your oven to 400°F (200°C). Line a baking dish with parchment paper or lightly grease it.
Arrange the marinated chicken thighs in the prepared baking dish, skin side up. Pour any remaining marinade over the chicken.
Bake in the preheated oven for 35-40 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (74°C). The skin should be golden and crispy.
Remove from the oven and let the chicken rest for 5 minutes before serving. Garnish with chopped parsley.