Pat the chicken thighs completely dry with paper towels. This step matters more than people think, since a dry surface is what gives you crispy skin. Toss the thighs in a bowl with the salt, pepper, and smoked paprika until every piece is evenly coated. Let them sit for a few minutes while your skillet heats up so the seasoning can settle in.
Heat the olive oil in your oven-safe skillet over medium-high heat until it's shimmering. Place the chicken thighs skin-side down and let them sear undisturbed for about 5-6 minutes. Resist the urge to move them around, since that's what builds a deep golden crust on the skin.
Flip the chicken thighs over and cook the other side for another 4-5 minutes. The chicken doesn't need to be fully cooked through at this stage you're just building color and flavor. Once both sides are golden, transfer the chicken to a plate and set it aside.
Lower the heat to medium and melt 2 tablespoons of butter in the same skillet, scraping up any browned bits from the bottom. Add the minced garlic and cook for about a minute until it's fragrant but not browned. Pour in the chicken broth and lemon juice, letting everything bubble together for a minute or two.
Stir in the remaining butter, dried oregano, and lemon slices, letting the sauce simmer gently until it thickens slightly. This is where the magic happens: the butter turns glossy and rich while the lemon keeps it bright instead of heavy. Taste it and adjust the salt if needed.
Preheat your oven to 400°F while the sauce simmers. Nestle the chicken thighs back into the skillet, skin-side up, spooning a little sauce over the top of each piece. Transfer the skillet to the oven and bake for 18-20 minutes, or until a meat thermometer reads 165°F at the thickest part.
Pull the skillet out of the oven and let the chicken rest for about 5 minutes before serving. Sprinkle the fresh parsley over the top and add a few extra lemon slices for color. This little resting step keeps all those juices locked inside the meat instead of running out onto the plate