Preheat the oven to 400°F (200°C).
Pat chicken thighs dry and season both sides with paprika, garlic powder, onion powder, thyme, salt, and pepper.
In a small bowl, whisk together melted butter, minced garlic, and lemon juice.
Place chicken thighs in a baking dish and pour the butter mixture over the top.
Arrange lemon slices around and on top of the chicken.
Bake uncovered for 35–40 minutes, until chicken is golden and reaches an internal temperature of 165°F (74°C).
Garnish with fresh parsley before serving.