Preheat the oven to 400°F and lightly grease a foil lined baking sheet.
Butterfly the chicken breasts and season both sides with salt, pepper, garlic powder and onion powder and place them onto the baking sheet.
In a small bowl, stir the Boursin cheese with the milk until smooth, creamy and easily spreadable. Spread the Boursin mixture evenly over the top of each piece of chicken.
In another bowl, toss the Panko breadcrumbs with olive oil and a little additional salt and pepper. Sprinkle the Panko mixture generously over the Boursin layer, gently pressing it down so it sticks.
Bake for about 12–15 minutes, or until the chicken is nearly cooked through and has reached a safe internal temperature. Move the baking sheet to the upper rack and broil for 1–2 minutes, watching it very closely, until the breadcrumb topping is crispy and golden brown. Remove the chicken from the oven, let it rest for a few minutes and serve warm.