In a shallow bowl, combine flour, shredded Parmesan, garlic powder, salt, and pepper. Dredge the chicken breasts in the mixture, coating both sides well. Shake off excess flour.
Heat a large skillet over medium-high heat. Add olive oil and butter.
Once the butter melts, add the chicken to the skillet. Cook for 3–5 minutes per side until golden brown and fully cooked. Remove chicken and set aside on a plate.
In the same skillet, add the chopped onion and cook for about 5–7 minutes until translucent.
Add the garlic cloves and sauté until soft and fragrant.
Pour in a small amount of chicken broth to deglaze the pan, scraping up the browned bits for extra flavor.
Add the remaining broth and heavy cream. Bring the mixture to a gentle simmer, then reduce heat to medium and stir occasionally until the sauce thickens.
Stir in grated Parmesan cheese until melted and smooth. Season with salt and pepper.
Return the chicken to the pan along with any juices. Cook for about 2 minutes, spooning the sauce over the chicken.
Garnish the Creamy Garlic Butter Chicken with chopped parsley and extra Parmesan before serving.