Cupcakes:
Preheat the oven to 350F (180 C).
Cover the small muffin molds with paper cups.

Beat the butter with the sugar using an electric mixer for 3 minutes.
Add the egg whites and eggs and mix well.
Add the flour, cocoa powder, baking powder, and salt, which have been previously sifted, and mix well.
Fill the molds 2/3 with the dough.

Bake for 15 to 18 minutes or until a toothpick inserted into the center comes out clean.
Remove the cupcakes from the muffin mold and place them on a rack to cool completely.

Homemade Marshmallow:
In a saucepan, combine the water, corn syrup, and sugar.
Bring to a boil until the candy thermometer reads 235 F (113 C).
Sprinkle the gelatin over the cold water and let it dissolve.
Remove the syrup from the heat, add the gelatin, and mix.
Beat the egg whites until soft peaks form and pour the syrup into the egg whites.
Add the vanilla and continue to beat for 3 minutes.
Transfer to a piping bag.

Place the marshmallow piping bag in the center of each cupcake.
Sprinkle with small candies and place a larger one in the center.
Let it rest for 2 hours at room temperature.