01 -
Read the actual cake-mix box and gather all required water, eggs and oil; prepare the batter with those amounts and the teaspoon of mint extract.
02 -
Bake in a prepared 13-by-9-inch pan at the temperature and time appropriate to that mix and pan, checking the cake as directed on the package.
03 -
Let the cake firm enough to handle, beginning the check after about twenty minutes, then make holes roughly an inch apart without destroying the crumb.
04 -
Whisk condensed milk and Irish cream and pour gradually across the cake so it enters the holes; the liqueur is added after baking and remains alcoholic.
05 -
Cover appropriately and refrigerate at least four hours, keeping total room-temperature handling within two hours.
06 -
Spread thawed whipped topping over the chilled cake, add mint baking chips, slice and return remaining cake to the refrigerator.