Preheat the oven to 350°F (175°C). If the chicken breasts are thick, slice them in half lengthwise. Season with salt and pepper.

Heat the oil in an oven-safe skillet over medium heat until very hot. Add the chicken and cook for 3-4 minutes per side, until browned but not cooked through. Transfer the chicken to a plate.

Add the butter to the same skillet. Once melted, add the garlic and cook for about 30 seconds, until fragrant. Add the lemon slices, lemon juice, and a pinch of salt. Cook for 2-3 minutes, turning the lemon slices once.

Return the chicken to the skillet (or transfer the chicken and sauce to a baking dish). Bake for 15-20 minutes, or until the chicken is fully cooked through. Serve.