Slice chicken breasts in half horizontally to create four thin cutlets. Pat thoroughly dry with paper towels. Season both sides with garlic powder, onion powder, paprika, 1/2 tsp kosher salt, and black pepper. Lightly dust both sides in flour, tapping off any excess.

Heat olive oil and 1 tablespoon of butter in a large heavy skillet over medium-high heat. Once sizzling, add chicken cutlets in a single layer. Sear undisturbed for 4 to 5 minutes per side until deep golden brown and cooked through to an internal temperature of 165°F (74°C). Transfer cutlets to a plate.

Lower heat to medium. Melt the remaining 1 tablespoon of butter in the skillet, add minced garlic, and sauté for 40 seconds until fragrant. Pour in chicken broth, scraping up all flavorful browned fond from the bottom of the pan. Simmer for 2 minutes until reduced by half. Pour in room-temperature heavy cream, lemon juice, and lemon zest. Whisk continuously as it gently simmers for 2 to 3 minutes until smooth and slightly thickened.

Whisk in freshly grated parmesan cheese until melted and velvety. Stir in fresh baby spinach for 1 minute until tender and wilted. Return seared chicken cutlets and any accumulated resting juices into the skillet. Spoon sauce over chicken, simmer for 1 minute, garnish with chopped parsley and lemon rounds, and serve hot immediately!