Preheat the oven to 350 degrees F. Line 2 muffin pans with cupcake liners.

Prepare the chocolate cake mix based on the box instructions.  Then fill each cupcake liner with the batter until they are about 2/3 of the way full.

Bake the cupcakes for 14-15 minutes until a toothpick inserted into the middle of the cupcakes comes out clean.  Then cool the cupcakes completely on a wire rack.

While the cupcakes are cooling, prepare the frosting.

In a large bowl cream butter and vegetable shortening until smooth with a stand up mixer or a hand held mixer.

Beat in powdered sugar (one cup at a time) on low speed until well combined.

Stir in vanilla and milk until thoroughly mixed and fluffy on a medium-high setting.

Pour the frosting into a piping bag fitted with a star tip.

Cut each of the cupcakes in half by cutting off the tops and place the bottom of the cupcakes into a mason jar.

Pipe a layer of frosting on top of each cupcake bottom in the mason jars. Then top with sprinkles.

Add the cupcake tops into each mason jar on top of the frosting layer.

Then pipe 1 more layer of frosting on top of the 2nd layer of cupcake in the mason jar.

Top with more sprinkles.

Refrigerate until ready to serve.  Then enjoy!