Preheat oven to 350 degrees F (175 degrees C). Grease two 9-inch square baking pans.

Mix brownie mix, oil, eggs, and water together in a bowl until batter is smooth; spread into the prepared pans.

Bake in the preheated oven until brownies are cooked through and edges are beginning to pull away from sides of pan, 20 to 25 minutes. Cool brownies.

Cut cooled brownies with a shot glass or small cookie cutter so they are slightly larger than the vanilla wafer. Put a small dot of chocolate frosting on the bottom and top of each "burger".

Make a rim around half of 60 vanilla wafer "top buns" with red gel representing the ketchup. Sandwich the "burger" with 2 vanilla wafers, with the "ketchup" wafers on top.