There is no one definitive answer to this question, as there are many recipes for chocolate cake that take 18 minutes or less to prepare. However, some examples of chocolate cake recipes that can be prepared in 18 minutes or less include a chocolate mug cake recipe, a one-minute chocolate cake recipe, and a chocolate lava cake recipe.
COMBINE FLOUR, SUGAR, SALT AND COCOA IN A LARGE BOWL.
MIX IN A SAUCE PAN, WATER, OIL AND BUTTER.
BRING TO A BOIL.
POUR INTO DRYMIX AND BEAT UNTIL SMOOTH.
ADD BUTTERMILK, EGGS AND SODA.
BEAT; BATTER WILLBE THIN.
POUR INTO WELL GREASED JEELY ROLL PAN.
COOL ON A WIRE RACK; WHILE STILL A LITTLE WARM, FROST WITH ROCKY ROADFROSTING (SEE RECIPE ON PAGE XX).