Preheat the oven to 325°F, and line two muffin pans with liners. Set aside.

In a large mixing bowl, combine the cake mix, instant pudding, eggs, water, and canola oil together with a stand or hand mixer. Use a spatula to fold in the chocolate chips. 

Fill each cupcake liner about ¾ of the way full with the chocolate batter. 

Bake for 30 minutes, then remove the cupcakes from the oven. Place a large marshmallow in the center of each cupcake, and twist gently as the marshmallows are being pressed. Return the cupcakes to the oven for 2 minutes, and allow the marshmallows to melt.

Remove the cupcakes from the oven a second time, and gently press the marshmallow down with your fingers (this will help the marshmallow melt on the inside of the cupcake and fill in the extra space around the cupcake). Let cool for 10 minutes in the cupcake pan before transferring to a cooling rack.

While the cupcakes cool, make the frosting by combining the powdered sugar, cocoa powder, water, and vanilla in a medium sized bowl. Mix until smooth. 

Fill the marshmallow indention with mini chocolate chips, then drizzle with frosting. Cut large marshmallows in half, and place the marshmallow halves on top of the mini chocolate chips. Drizzle additional frosting over the top.

Garnish with Peppermint Crunch Sprinkles and holiday straws. Enjoy! Store any leftovers in an airtight container for 4 days.