Preheat oven to 325 degrees. Grease the bottom of a 9-inch by 9-inch pan. In a large bowl, combine brownie mix, eggs, oil, and water. Pour into greased pan and bake until done, about 40 minutes. Cool. Cut into 1-inch squares.
In a large bowl, combine the pudding mix, vanilla, water, and sweetened condensed milk. Mix until smooth, then fold in 8 ounces of whipped topping. Fold until no streaks remain.
In a trifle bowl or glass serving dish, place half of the brownies, half of the pudding mixture and 4 ounces of remaining whipped topping. Repeat layers. Garnish with crumbled Oreo cookies. Refrigerate 2 hours before serving.
Brownies: Of course you can make homemade Brownies from scratch to cube and layer into this dish, but I love to save time with the semi-homemade route. No one will notice you started with boxed brownie mix, promise!
Sweetened condensed milk: Combining this with the boxed chocolate pudding mix makes its consistency remarkably silky and rich.
Whipped topping: Cool Whip is a Midwestern staple, although any brand will do. Or, substitute an equal amount of whipped cream.
Oreo cookies: Since this chocolate dessert recipe is all about the chocolate, I recommend the classic Oreos. If desired, choose any alternative Oreo cookie flavor that fits the season or your preferences; Chocolate Hazelnut, Mint, or Dark Chocolate would also be delightful in this trifle recipe.