Slice boneless skinless chicken breasts into thinner cutlets and season both sides with garlic powder, salt, and black pepper.

In a large skillet, heat olive oil and half of the butter over medium-high heat. Once hot, add the seasoned chicken cutlets. Cook for 5-6 minutes on each side until golden brown and cooked through.

Reduce heat to medium and add remaining butter to the skillet. Add sliced onions and sauté for 10-15 minutes until softened and lightly caramelized.

Stir in minced garlic and cook for an additional 30 seconds until fragrant.

Pour in chicken broth and Worcestershire sauce, scrapping up any browned bits. Simmer for flavor.

Lower heat and stir in full-fat sour cream until smooth and combined.

Return the seared chicken to the skillet, spooning sauce over each piece. Let simmer for a couple of minutes.

Taste and adjust seasoning if needed. Garnish with freshly chopped parsley before serving.