Prep:
Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish.
Cook shells al dente (1–2 mins less than package says). Drain, rinse with cool water, and pat dry.
Make Filling:
In a bowl, mix chicken, broccoli, 1 cup cheddar, garlic powder, salt, and pepper.
Pro Tip: For creamier filling, stir in sour cream/cream cheese or a splash of the pasta cooking water.
Stuff Shells:
Spoon 2 tbsp filling into each shell. Arrange snugly in the dish.
Make Sauce:
Whisk soup and milk until smooth. Pour evenly over shells.
Optional: Add a pinch of thyme or onion powder to the sauce.
Bake:
Sprinkle with remaining ½ cup cheese (and Parmesan, if using).
Bake 25 mins until bubbly. Broil 2–3 mins for a golden top.
Rest 5 mins before serving.