Pat chicken cutlets thoroughly dry with paper towels. Season both sides evenly with sea salt, black pepper, garlic powder, and oregano.

Heat olive oil and butter in a large 12-inch cast iron skillet over medium-high heat until hot and shimmering.

Sear chicken cutlets undisturbed for 4 to 5 minutes per side until deeply golden and cooked through (internal temp 165°F). Transfer to a warm plate and set aside.

Lower skillet heat to medium. Add minced garlic and sauté for 60 seconds until fragrant. Pour in chicken bone broth, using a wooden spoon to scrape up all the golden browned bits (fond) from the pan bottom.

Pour in heavy whipping cream and sliced sun-dried tomatoes. Bring to a gentle simmer for 3 minutes until the sauce slightly thickens.

Stir in grated parmesan cheese and fresh baby spinach in batches. Cook for 2 minutes until spinach is wilted and cheese is completely melted into a glossy sauce.

Nestle the seared chicken cutlets and any plate juices back into the skillet. Spoon the creamy sauce over top, simmer for 1 minute to warm through, garnish with fresh basil, and serve immediately.