Mix together 1 pound cake mix with 6 oz water and 1 oz vegetable oil. Mix on low speed until mixture comes together, then on second speed for 2 minutes. Using the # 40 purple scoop, scoop out cake circles, bake at 375°F until completely set and cakes spring back lightly when touched. Let cool completely.
Irish Creme Filling: Combine 2 pounds Holland Creme and 1.5 oz Irish Creme Liqueur.
Whiskey Filling: Combine 2 pounds Holland Creme and 1.5 oz Whiskey.
Coffee Liqueur Filling: Combine 2 pounds Holland Creme, 1.5 oz Kahlua and 1 tsp coffee extract.
Fill whoopie pies with desired filling, top with another pie, roll in desired garnish and serve.