First, combine the chicken legs, melted butter, olive oil, dried oregano, smoked paprika, minced garlic, lemon juice, salt, and pepper in a large ziploc bag. Seal the bag tightly and toss everything together until the chicken is thoroughly coated. This method is fantastic because it minimizes cleanup.
Place the sealed bag in the refrigerator and let the chicken marinate for at least 30 minutes. If you have more time, letting it marinate for a few hours or even overnight will allow the flavors to penetrate the meat more deeply, resulting in an even more delicious final product.
When you're ready to cook, preheat your oven to 450°F (232°C). This high temperature is crucial for achieving that perfectly crispy skin and juicy interior. Arrange the marinated chicken legs in a single layer in a large casserole dish, making sure they aren't too crowded.
Tuck the fresh lemon slices in between the chicken legs in the dish. Bake uncovered for 30 to 35 minutes. The chicken is done when it’s golden brown and the internal temperature reaches 180-185°F. Let it rest for a few minutes before garnishing with fresh thyme and serving warm.