French silk brownies

1 box brownie mix, not prepared
1 egg
5 1/2 tablespoons unsalted butter, melted
1/4 cup milk

French silk layer:
8 ounces cream cheese, at room temperature
1 teaspoon vanilla extract
2 cups powdered sugar
4 ounces semi-sweet chocolate
1/4 cup unsalted butter, cubed
8 ounces whipped topping

Topping:
8 ounces whipped topping
Chocolate shavings or mini chocolate chips

Preheat oven to 350 degrees. Grease a 2-quart glass baking dish with non-stick cooking spray. In a medium mixing bowl, combine the brownie mix, egg, melted butter and milk, stirring until smooth. Spread the batter into the prepared baking dish and bake for 25-28 minutes until a toothpick inserted into the center comes out clean. Remove the brownies from the oven and cool completely to room temperature. In a large mixing bowl, beat the cream cheese and vanilla extract with an electric mixer until smooth and creamy. Add the powdered sugar and mix until combined. In a small microwave-safe bowl, heat the semi-sweet chocolate and unsalted butter in 30-second intervals until melted, stirring well between each cooking interval. Add the melted chocolate and butter mixture to the cream cheese mixture and stir until combined. Gently fold in the whipped topping. Spread the French silk layer over the cooled brownies, then spread on the remaining 8 ounces of whipped topping. If desired, sprinkle chocolate shavings or mini chocolate chips over the French silk brownies.