For the Chocolate Cupcakes:

1. Preheat Oven: Preheat the oven to 350°F and line cupcake pans with 24 paper liners.
2. Cream Butter and Sugar: Beat the butter, granulated sugar, and brown sugar on medium-high speed until light and fluffy, about 5 minutes. Add eggs one at a time, beating well after each addition. Add vanilla extract and mix well.
3. Mix Wet Ingredients: In a separate bowl, whisk together the chocolate milk, sour cream, and water (or coffee).
4. Mix Dry Ingredients: In another bowl, sift together the flour, cocoa powder, baking soda, and salt.
5. Combine: With the mixer on low speed, alternate adding the dry ingredients and the wet mixture, starting and ending with the dry ingredients. Mix until just incorporated. Finish combining with a spatula, scraping the sides of the bowl.
6. Bake: Scoop the batter into the lined cupcake pans. Bake for 20-22 minutes, until the tops spring back when lightly pressed. Let cool completely before decorating.

For the Triple Chocolate Frosting:

1. Melt Chocolate: Melt the chopped chocolate in the microwave in 30-second increments, stirring after each, until smooth. Let it cool.
2. Mix Frosting: In a large bowl, beat the powdered sugar, cocoa powder, butter, and salt on low speed until moistened. Gradually add the chocolate milk and vanilla, then beat on medium speed until light and fluffy, about 4 minutes.
3. Add Melted Chocolate: Pour the cooled melted chocolate into the frosting, mix on low, then increase speed to medium and beat for another minute.

For Stamped Fondant Circles:

1. Prepare Fondant: Dust your work surface with powdered sugar and roll the fondant to about 1/8” thick. Use a circle cutter to cut out 24 fondant circles. Let them sit overnight or in a low-temperature oven to harden.
2. Make Edible Stamp Pad: Place felt in a plastic lid and spritz lightly with water. Add gel food coloring and use a brush to spread it evenly. Press the clean stamp onto the felt and do a few test stamps before pressing onto the fondant circles.
3. Decorate: Once the stamped fondant dries, brush the edges with corn syrup and roll them in sparkling sugar for an extra touch.

Assemble:

1. Frost Cupcakes: Use a piping bag fitted with a large star tip to swirl the frosting on top of each cupcake.
2. Add Sprinkles: Press chocolate sprinkles into the base of the frosting for extra decoration.
3. Top with Stamped Fondant: Place the stamped fondant circles on top of each cupcake.