Bake the Cake: Prepare the white cake mix according to the package directions. Bake in a greased 9x13 inch baking pan.
Cool Slightly: Let the cake cool for about 15 minutes.
Poke Holes: Use a wooden spoon or the end of a spatula to poke holes all over the cake, about 1 inch apart.
Prepare Pudding: In a mixing bowl, whisk together the instant vanilla pudding mix and milk until smooth. Stir in a few drops of green food coloring until you reach your desired shade of green.
Pour Pudding over Cake: Slowly pour the green pudding mixture over the cake, making sure to fill all of the holes.
Chill: Cover the cake with plastic wrap and refrigerate for at least 2-3 hours, or until the pudding has set.
Frost: Spread the thawed whipped topping evenly over the chilled cake.
Sprinkle: Sprinkle with St. Patrick's Day sprinkles.
Serve and Enjoy!