Before anything else, butterfly the chicken breasts lengthwise to create thinner, more uniform pieces. This ensures even cooking and shortens the cook time. Combine the flour, garlic powder, salt, and pepper in a shallow dish, then dredge the chicken. Lightly press the chicken into the mixture to coat both sides, shaking off any excess.
Heat one tablespoon of butter and olive oil in a large frying pan over medium-high heat. Once the mixture starts bubbling, add the chicken. Cook each side for about 3–5 minutes until golden brown and thoroughly cooked. Remove the chicken from the pan and set aside.
Reduce the heat to medium and toss in the minced garlic. Stir for about a minute until fragrant but not burnt. Pour in the chicken stock, using a wooden spoon to scrape up any browned bits from the pan. Gradually add the remaining butter, whisking as it melts to form a rich, velvety sauce.
Stir in the chopped parsley to brighten the flavor. Return the cooked chicken to the pan, spooning the sauce over each piece. Allow it to simmer on low heat for a couple of minutes so it can soak up all the flavors before serving.