Preheat oven to 350°F and line a 12x15" sheet pan with parchment paper or a silicon baking mat. Use oil or cooking spray to grease the walls of the pan and set aside.
In a mixing bowl with a whisk attachment, beat the eggs.
Add the sugar, water and vanilla and mix well.
Sift in the flour, cocoa powder, baking powder and salt.
Pour the batter into the prepared pan and bake for 17-18 minutes.
Let the cake cool for 5 minutes (no longer!).
Take the cake out of the pan and place on a cloth dusted with powdered sugar.
Roll the cake up (with the cloth) and leave on the counter until completely cool.
When cooled, unroll the cake, remove the cloth and cover with ice cream. I've found that it works best to scoop the ice cream on top, let it soften for 5 minutes, then spread it so it's nice and smooth.
Re-roll (you'll want to roll from the short side of the cake) and wrap in plastic wrap to freeze.
Freeze for 6+ hours. Remove from the freezer 20-30 minutes before serving.
To make the chocolate ganache, in a microwave-safe bowl, heat the 1/2 cup whipping cream until hot (but not quite boiling). Add the chocolate chips and let sit for 5 minutes before stirring. Stir until smooth.
To serve, place the ice cream roll on a platter, pour ganache overtop, dollop with whipped cream and garnish with Oreos and sprinkles.
Slice and enjoy!