Preheat the oven to 350 degrees. Add the cupcake liners to the cupcake pan.
Add the cake mix to a bowl and mix in the eggs, old, and soda on medium speed with a mixer. Add 1 cup of cocoa powder.
Put the batter into the liners about 2/3 full. Bake for 18-20 minutes. Let cool.
Frosting:
Cream the butter with a mixer in a bowl. This will take about 2 minutes.
Mix in the cocoa powder and syrup.
Add the half and half and soda together in a different bowl. (this is important!)
Mix the powdered sugar 1 cup at a time while pouring in a little bit of the liquid mixture between each cup of sugar. Mix for 1-2 minutes but don't mix it too much.
Put in the piping bag and frost. Add sanding sugar and straw.