Heat olive oil in a large deep skillet or Dutch oven over medium-high heat until shimmering.
Season chicken thighs evenly with salt and black pepper on both sides.
Place chicken thighs skin-side down in the hot skillet and sear for 5-6 minutes until the skin is golden brown and crispy. Flip and cook the other side for 3-4 minutes. Remove chicken from the skillet and set aside.
Reduce heat to medium. Add minced garlic to the skillet and sauté for 1 minute until fragrant, stirring constantly to avoid burning.
Pour in chicken broth and fresh lemon juice, scraping the bottom of the skillet with a wooden spoon to loosen any browned bits.
Add lemon slices, dried oregano, and dried thyme to the skillet. Stir to combine.
Return the chicken thighs to the skillet, skin-side up. Spoon some of the sauce over the chicken.
Cover the skillet and reduce heat to low. Simmer for 15-18 minutes until the chicken is cooked through and reaches an internal temperature of 165°F (74°C).
Remove the lid and add unsalted butter to the skillet. Spoon the melted butter and sauce over the chicken.
Sprinkle chopped fresh parsley over the chicken before serving.
Serve the chicken hot with the lemon slices and pan sauce spooned over the top.