Step 1
Preheat the oven to 375 degrees F (190 degrees C). Coat 30 cupcake cups with butter and flour.
Step 2
Mix flour sugar cocoa baking soda baking powder and salt together in a large bowl. Beat milk oil eggs and vanilla extract together in another large bowl; slowly add dry ingredients and mix well.
Step 3
Spoon batter into the prepared muffin cups filling each about 1/2 full.
Step 4
Bake in the preheated oven until tops spring back when lightly pressed 15 to 17 minutes. Take cupcakes out of tins and let cool completely 10 to 15 minutes.
Step 5
Meanwhile combine confectioners' sugar butter shortening milk vanilla extract and salt for filling together in a bowl; beat until well whipped. Reserve about 1 1/2 cups of filling mixture for decorating cupcakes. Add marshmallow creme to the rest of the filling. Fill a pastry bag fitted with a long thin tip with the marshmallow mixture. Pipe into cooled cupcakes; let cream settle.
Step 6
Mix confectioners' sugar cocoa butter evaporated milk and vanilla extract together for icing in a bowl until creamy. Mix in chocolate chips and corn syrup. Transfer to a microwave-safe bowl and microwave mixture on high for 30 seconds. Stir and repeat process until smooth.
Step 7
Dip the tops of the cupcakes into the fudge icing and set aside to dry.
Step 8
While icing is drying place reserved filling for decorating into another pastry bag fitted with a writing tip. Decorate cupcakes as desired.