Prepare the Creamed Chicken:

Preheat your oven to 375°F (190°C).

In a large skillet, melt the butter over medium heat.

Add the diced onion and minced garlic, and sauté until softened and fragrant.

Sprinkle the flour over the onion and garlic mixture, stirring constantly to form a roux.

Gradually whisk in the chicken broth and heavy cream, stirring until the sauce thickens.

Add the cooked chicken and frozen peas to the skillet, stirring until heated through.

Season with salt, black pepper, and chopped parsley, then remove from heat.

Prepare the Biscuit Topping:

In a mixing bowl, whisk together the flour, baking powder, and salt.

Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs.

Gradually pour in the milk, stirring until a soft dough forms.

Assemble the Casserole:

Transfer the creamed chicken mixture to a greased 9×13-inch baking dish, spreading it evenly.

Drop spoonfuls of the biscuit dough over the top of the chicken mixture, covering it completely.

Sprinkle shredded cheddar cheese over the biscuit topping, if desired, for extra flavor.

Bake the Casserole:

Place the assembled casserole in the preheated oven and bake for 25-30 minutes, or until the biscuits are golden brown and cooked through.

Remove from the oven and let it cool for a few minutes before serving.

Serve and Enjoy:

Spoon generous portions of the creamy chicken and biscuit casserole onto plates.

Garnish with additional chopped parsley, if desired, and serve hot.