Using an electric mixer, beat the cream in a big mixing bowl. Gradually add in the sugar and vanilla. Keep on beating it until you get stiff peaks in the cream. To test it, lift the beater right up. Ideally, the cream should create a peak that holds its shape.

Spread a teaspoon (plus a little extra) of whipped cream onto each cookie, then press the cookies together to make stacks. Each stack should be about three inches tall.

Spread an inch-wide line of whipped cream down center of a serving platter. Assemble the cookie stacks along the cream line into a log shape.

Use the leftover cream to frost the log, then sprinkle it with grated chocolate.

Put a cover over the log, and make sure it's nice and tight. Leave the cake in the fridge overnight to harden.

Slice the cake diagonally to see the black and white stripes.