Preheat the oven to 350°F (175°C) and grease a 9x13-inch casserole dish.

In a large skillet over medium heat, cook 1 pound of ground beef, seasoning with salt and pepper for 5-7 minutes until browned. Drain any excess fat.

Blend 6 oz. of cream cheese in a food processor until smooth, then add 3 eggs gradually until fully integrated.

Melt 2 tablespoons of butter in the same skillet; add 5 cups of mushrooms and sauté for 5-7 minutes until golden brown. Season with salt, pepper, and dried parsley.

Layer the creamy beef mixture in the greased casserole dish, add the sautéed mushrooms on top, and sprinkle with grated cheese if desired.

Bake the assembled casserole in the oven for 20-25 minutes until golden and firm in the center.

Let the casserole cool for 5-10 minutes before serving.