Step 1: Pat chicken breasts completely dry with paper towels. Pound them to an even 1/2 to 3/4-inch thickness if needed.
Step 2: In a small bowl, combine salt, pepper, garlic powder, onion powder, and paprika. Season both sides of the chicken generously with this mixture.
Step 3: Heat a large, heavy-bottomed skillet over medium-high heat. Add 1 tablespoon of olive oil and swirl to coat the pan until shimmering.
Step 4: Carefully place the seasoned chicken breasts in the hot skillet. Sear for 4-6 minutes per side, undisturbed, until a deep golden-brown crust forms.
Step 5: Reduce heat to medium-low. Add the remaining 1 tablespoon of olive oil, minced garlic, fresh rosemary, and fresh thyme to the pan. Cook for 1-2 minutes, stirring the garlic and herbs around the chicken, until fragrant and lightly golden.
Step 6: Deglaze the pan by pouring in the chicken broth and lemon juice. Use a wooden spoon to scrape up any browned bits from the bottom of the pan.
Step 7: Add the lemon slices to the pan, nestling them around the chicken. If using, add the unsalted butter. Continue to cook for another 2-4 minutes, spooning the pan sauce over the chicken occasionally, until the chicken reaches an internal temperature of 165°F (74°C).
Step 8: Remove the chicken from the skillet and transfer to a cutting board. Tent loosely with foil and let it rest for 5-10 minutes.
Step 9: While the chicken rests, you can reduce the pan sauce slightly over medium heat if desired. Remove the herb sprigs. Slice the chicken against the grain, if serving sliced. Drizzle generously with the pan sauce and garnish with fresh chopped parsley and lemon zest. Serve immediately.