Preheat the oven to 350°F. Line a 12 count cupcake tin with cupcake liners, set aside.

In the bowl of a stand mixer with the paddle attachment, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until combined.

Add in the vanilla and eggs, stir until combined. Add the milk, water, and oil, stir until smooth. I like to take a whisk and whisk it by hand a few times to make sure there are no lumps.

Fill the cupcake liners ⅔ of the way full and bake for 18-20 minutes until a toothpick inserted into the center comes out clean. Let cool in the tin for 5 minutes. Take the cupcakes out and cool completely on a wire rack.

While the cupcakes cool, make the marshmallow frosting.

Place the egg whites, sugar, cream of tartar, and sea salt in the body of a stand mixer or a large bowl. Whisk to combine.

Place over a medium-sized saucepan with 2 inches of simmering water. Whisk constantly until the mixture reaches 160°F. It will become thinner. You will notice the bottom of the mixture will be a clear tone with a foamy layer on top.

Take off the heat and add the vanilla.

Place this on the stand mixer with the whisk attachment or with an electric hand mixer, whip until stiff peaks form on medium-high speed.

The frosting will become bright white and glossy. Use immediately.

Once the cupcakes are cool, pipe the frosting on top. I like to use the open tip of a piping bag or a ½ inch tip. Leave a ¼ inch border around the cupcake, do not pipe all the way to the edge. Place the frosted cupcakes into the refrigerator for 30 minutes.

Make the coating by placing the chopped chocolate and 3 tablespoons of butter in a microwave safe bowl. Microwave for 30 seconds, stir. Microwave another 30 seconds and stir. Continue to microwave at 15 second intervals stirring in between until smooth. If the mixture is too thick, add an additional 1 tablespoon of butter to thin it out. We need it to be thin enough to dip the cupcakes in. Let cool for 5 minutes.

Very quickly invert the cupcakes and dip the tops into the melted chocolate. Make sure all of the frosting is covered. Let any excess chocolate drip off.

Place the cupcake right side up back onto the wire rack, with parchment paper or a sheet tray under it to catch any drips. If using sprinkles, add them on immediately. Place them back in the fridge for 30 minutes to set.