Preheat your oven to 375°F (190°C).
Lightly season the chicken breasts with salt and pepper on both sides.
Place the chicken in a greased baking dish.
In a medium bowl, whisk together brown sugar, pineapple juice, crushed pineapple, and soy sauce until well combined.
Pour the pineapple mixture evenly over the chicken.
Bake uncovered for 30–35 minutes, or until the chicken is fully cooked and tender.
Remove the chicken from the baking dish and set aside.
Transfer the sauce to a small saucepan. Mix cornstarch with water and stir into the sauce. Simmer over medium heat until thickened.
Spoon the thickened pineapple glaze over the chicken and garnish with chopped green onions and sesame seeds if desired.
Serve warm with your favorite sides like rice or vegetables.