Butterfly the chicken breasts. Dip each piece in egg wash (eggs whisked with milk), then coat with bread crumbs mixed with garlic powder, salt, pepper, and poultry seasoning.
In a 15” cast iron skillet, heat avocado oil and fry the chicken until golden brown on both sides. Set aside.
Remove excess oil from the skillet. Add 2 tbsp of butter, onion, and garlic, letting them cook until softened. Then add the rest of the butter, lemon juice, chicken stock, and flour, cooking for 5 minutes to thicken.
Add capers and heavy cream, bringing the sauce to a boil. If using pasta, add now and let it cook until tender.
Return the chicken to the skillet, cover, and cook for 5 minutes. Top with Parmesan and serve warm.