Preheat your oven to 425°F (220°C).
In a large bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, oregano, salt, black pepper, paprika, and red pepper flakes if using.
Add the chicken thighs to the bowl and toss to coat them evenly in the marinade. Let them marinate for at least 30 minutes at room temperature, or refrigerate for up to 2 hours for more flavor.
While the chicken is marinating, place the halved baby potatoes in a separate bowl. Drizzle with a little olive oil and season with salt and pepper, tossing to coat.
In a large baking dish, arrange the marinated chicken thighs skin-side up. Surround them with the seasoned potatoes.
Pour any remaining marinade over the chicken and potatoes.
Bake in the preheated oven for 45-50 minutes, or until the chicken is cooked through (internal temperature should reach 165°F) and the potatoes are tender and golden.
Optional: For extra crispy skin, broil for an additional 2-3 minutes at the end of cooking.
Remove from the oven and let rest for 5 minutes before serving. Garnish with chopped parsley.