Preheat the oven: Set your oven to 375°F (190°C).
Cook the potatoes: Boil the cubed potatoes in salted water for about 10 minutes, until tender. Drain and set aside.
Blanch the broccoli: In the same pot, bring fresh water to a boil and blanch the broccoli florets for 3 minutes. Drain and set aside.
Prepare the sauce: In a large bowl, mix together the sour cream, milk, 1 cup of cheddar cheese, garlic powder, onion powder, salt, and pepper until smooth.
Combine ingredients: Add the cooked potatoes, diced chicken, and blanched broccoli to the sauce, stirring gently to coat everything evenly. Transfer the mixture to a greased 9×13-inch baking dish.
Add the topping: Mix breadcrumbs with melted butter in a small bowl. Sprinkle the remaining cheddar cheese over the casserole, followed by the breadcrumb mixture.
Bake: Bake in the preheated oven for 20-25 minutes, until the top is golden brown and bubbly.
Serve: Allow the casserole to cool for 5 minutes before serving.

PREP TIME & NUTRITION:
Prep Time: 20 minutes, Cook Time: 25 minutes, Total Time: 45 minutes, Servings: 6, Calories: 450, Net Carbs: , Fats: , Protein: