In a shallow dish, combine the flour, garlic powder, salt, and black pepper.
Butterfly each chicken breast through the center to create 4 even cutlets.
Dredge each piece of chicken in the seasoned flour, pressing lightly so the coating sticks well. Shake off any excess.
Heat 1 tablespoon of butter and the olive oil in a large skillet over medium-high heat.
Add the chicken and cook for 3 to 5 minutes per side, or until golden brown and fully cooked through. Transfer to a plate.
Reduce the heat to medium and add the minced garlic to the same pan. Cook for 1 to 2 minutes until lightly golden and fragrant.
Pour in the chicken stock and scrape up the flavorful bits from the bottom of the pan.
Add the remaining butter and whisk until melted and combined into a glossy sauce.
Stir in the parsley and season with extra salt and black pepper to taste.
Let the sauce simmer for a few minutes until it thickens slightly.
Return the chicken to the skillet and spoon the sauce over the top. This Garlic Butter Chicken is best served hot with extra sauce and a squeeze of fresh lemon juice.