Towering chocolate trifle

1
Preheat the oven to 325°F. Lightly grease a 9-by-13-inch baking pan. Prepare the brownie batter according to package directions using the egg, canola oil and water. Spread the batter into the pan and bake until a toothpick comes out clean, 18 to 22 minutes. Let the brownies cool completely in the pan. Set aside.
2
Meanwhile, prepare the pudding according to package directions using the milk. Chill for at least 30 minutes or up to overnight.
3
Beat the cream cheese and sugar on medium-high speed in the bowl of a stand mixer fitted with a whisk attachment until smooth and fluffy, 3 to 4 minutes. Reduce the speed to medium and gradually add the heavy cream and vanilla, beating until the cream is whipped and well combined with the cream cheese, 1 to 2 minutes, stopping occasionally to scrape the sides of the bowl.
4
Fold about 1 cup of the heavy cream mixture into the pudding to lighten.
5
To assemble, cut the brownies into 20 pieces. Place the chocolate sandwich cookies in a large zip-up bag. Coarsely crush the cookies using a rolling pin.
6
Arrange half of the brownies in an even layer in a 4-quart trifle dish. Top with half of the chocolate pudding, sprinkle with half of the cookie pieces and top with half of the remaining whipped cream cheese. Repeat the layers once more. Garnish with chocolate shavings. Serve immediately, or store in the refrigerator for up to 24 hours.