1 (15.25 oz) package chocolate fudge cake mix
½ cup butter, softened
⅔ cup shortening (such as Crisco)
¾ cup sugar
2 teaspoons vanilla extract
½ cup evaporated milk
1 (16 oz) can chocolate fudge frosting
Bake the cake mix in a 13×9 inch pan at 325°F according to the package guidelines. The lower temperature will aid in the prevention of the cake doming. Allow the cake to cool completely before serving.
After the cake has cooled, with a stand mixer, beat the butter, crisco, sugar, vanilla, and evaporated milk on high for 15 minutes. The finished product will be light and fluffy. Apply to the cooled cake.
Remove the lid from the frosting can and set it aside. Remove the foil seal entirely (if it doesn’t come off completely, see comments). Microwave the frosting can on high for 15 seconds. Stir in another 15 seconds in the microwave, or until the frosting is pourable.
Using a spatula, spread the frosting evenly over the cream layer. Allow to remain at room temperature for 2–3 hours until the frosting hardens, or fridge for 45 minutes. Serve by cutting into slices.