Combine brownie mix, water, vegetable oil, and eggs in a mixing bowl. (Be sure to use the ingredient amounts listed on the brownie box if different from above)
Bake according to the directions on the box. Let cool completely.
Scoop ice cream into mixing bowl and mix with an electric mixer until slightly melted. It should be about the consistency of soft-serve ice cream.
1.5 quarts Breyers Chocolate Ice Cream
Spread evenly over the top of the brownie layer. Freeze for at least two hours.
Spread whipped topping over the top of the ice cream.
8 ounces whipped topping
Drizzle with chocolate syrup, then add chocolate curls or sprinkles. Freeze for at least four hours (freeze overnight for best results).
3-4 tbsp chocolate syrup, chocolate curls or chocolate sprinkles
Notes
To cool brownies off faster, you can set the baking dish on top of a wire rack. That way, the air can get to the bottom of the pan and cool it more quickly.
Take the cake out of the freezer about 10-15 minutes before serving. This will give the brownie layer time to thaw enough to slice.