Preheat Oven: Preheat your oven to 375°F (190°C). Grease a baking dish (9×13 inches or similar) with butter or cooking spray.

Prepare the Cheese Sauce: In a medium saucepan over medium heat, melt the butter. Stir in the almond flour and cook for 1-2 minutes, until the mixture is slightly golden.

Gradually whisk in the heavy cream, ensuring no lumps form. Continue to cook, stirring frequently, until the sauce thickens.

Remove from heat and stir in the shredded cheddar cheese until melted and smooth. Season with garlic powder, onion powder, salt, and black pepper.

In a large bowl, mix the cooked chicken, broccoli, and half of the shredded cheddar cheese. Add the cheese sauce and stir until everything is well coated.

Pour the mixture into the prepared baking dish. Sprinkle the remaining shredded cheddar cheese and Parmesan cheese on top.

Bake in the preheated oven for 25-30 minutes, or until the casserole is bubbly and the top is golden brown.

Allow the casserole to cool for about 10 minutes before serving. This helps the flavors to meld and makes serving easier.