Cut the chicken breasts in half lengthwise to create four thinner pieces. Season each piece with garlic powder, salt, and pepper.
Heat olive oil and butter in a skillet over medium-high heat. Cook each piece of chicken for about 5–6 minutes on each side until golden brown and cooked through.
In the same skillet, add chopped onions and sauté for about five minutes until softened and lightly browned.
Pour in the chicken broth and softened Boursin cheese into the skillet. Stir until a smooth and creamy sauce forms. Let it bubble gently for five minutes.
Add the cooked chicken back into the skillet along with any juices. Warm through for a couple of minutes, adding more chicken broth if the sauce is too thick.
Taste the dish and season with salt and pepper as needed. Sprinkle parsley over just before serving.