Season the halved chicken breasts with garlic powder, chili powder, onion powder, paprika, kosher salt, and black pepper, ensuring an even coating.
Melt ½ cup of unsalted butter in a large skillet over medium-high heat. Add the seasoned chicken breasts and sear for about 5-6 minutes per side until golden brown. Remove from skillet.
Add the remaining ¼ cup of butter to the skillet. Once melted, add the diced onion and sauté for 3-4 minutes until translucent. Add minced garlic and cook for another minute.
Sprinkle the flour over the onions and garlic, stirring for about 1 minute. Gradually pour in the heavy cream, stirring constantly to avoid lumps. Bring to a simmer until slightly thickened.
Return the seared chicken to the skillet, spooning the creamy sauce over it. Simmer for an additional 2-3 minutes. Serve over cooked penne pasta and garnish with parsley.