Line a cookie sheet with parchment paper or a silicone nonstick baking mat. Set aside.
Add the cake mix, eggs, and oil to a large mixing bowl. Mix with an electric mixer at low speed until completely combined. (The batter will be really stiff!)
Either pinch off pieces of batter or use a small ice cream scoop and then use your hands to roll into 1-inch balls. Place 1 inch apart on the prepared cookie sheet. Use your hand or the smooth bottom of a measuring cup or glass to flatten the cookies slightly.
Bake for 8 to 10 minutes, until only a slight indention remains when you lightly touch the cookies.
Remove immediately from the cookie sheet with a spatula and cool on a wire rack.
Peppermint Filling Directions:
Place 1 cup of the confectioners' sugar and the shortening to a large bowl and beat with an electric mixer on medium speed until well combined. Add the rest of the sugar, and continue beating until everything is well combined. Finally, add the marshmallow creme, 1 tablespoon of milk, and peppermint extract, and beat until light and fluffy. This will take about 5 minutes.
Assemble the Whoopie Pies:
Spread a heaping tablespoon of the filling on one cookie. Place another cookie on top and gently press down to push the filling to the edge of the cookies.
Put the crushed candy canes on a plate and gently roll the sides of the cookies in the candy to coat.
The chocolate cookies used to make these whoopie pies are delicious all by themselves.
If you would like to change the filling up a bit, simply leave out the peppermint and add vanilla, almond extract or another flavor.
The hardest part of this recipe is removing the wrappers from individual candy canes. If possible purchase them unwrapped.
I used a food processor to chop up the candy canes, but you could also just place them in a heavy duty plastic bag and crush them with a hammer or rolling pin.