Preheat oven to 350°F Coat a baking pan with olive oil cooking spray.
Season chicken lightly with salt and pepper and place in baking dish; set aside.
Combine peanut butter, soy sauce and water (if you like thinner sauce add 1-2 tbsp more water) and stir until smooth and well mixed (or microwave on high 30 seconds). Spoon mixture over the chicken, then sprinkle with sesame seeds.
Bake for 20-30 minutes or until the chicken is no longer pink inside.