Heat oven to 325 degrees F. Lightly grease and line three 8-inch round cake pans with parchment paper.
Blend oil, water, and eggs together in a large bowl. Stir in brownie mix until moistened. Divide batter evenly into 3 pans.
Bake until a toothpick inserted into the center comes out clean, 38 to 40 minutes. Cool completely before removing from pans.
For Ganache: Place each type of chips into 3 bowls.
Heat cream in microwave at 30 seconds intervals until it just boils. Immediately pour 3/4 cup cream over each type of chips; stir until chocolate melts. Add 1/4 cup corn syrup to each; stir until shiny.
Let cool 2 hours before whipping with an electric mixer until fluffy.
Stack cooled brownie layers on a plate, spreading a different variety of ganache between each layer. Serve chilled.
