Slice the chicken breasts in half lengthwise to create 4 thinner pieces, then season both sides with garlic powder, salt, and pepper.

Heat olive oil and 1 tablespoon of butter in a skillet over medium-high heat. Add the chicken and cook for 5–6 minutes per side until golden and cooked through (165°F), then transfer to a plate. If it sticks, let it cook a bit longer—it will release naturally.

Reduce heat to medium, add the remaining butter and sliced onions, and cook for 10–15 minutes until soft and lightly browned, stirring occasionally. Lower the heat if they begin to burn.

Stir in the minced garlic and cook for about 30 seconds until fragrant.

Pour in the chicken broth and Worcestershire sauce, scraping up the browned bits from the pan to build flavor.

Lower the heat and stir in the sour cream until smooth. Let it warm gently for a couple of minutes, avoiding boiling to prevent curdling.

Return the chicken to the skillet, spoon the sauce over the top, and let it heat through for 2–3 minutes.

Taste and adjust seasoning if needed, then sprinkle with fresh parsley before serving.