1. Adjust your oven’s temperature to 350 degrees Fahrenheit and leave it to preheat.
2. Paper or foil liners should be used to line the 48 indents of mini muffin pans. You can also bake the mixture in batches if you only have one or two pans.
3. In a small glass bowl, place the chocolate. Microwave the chocolate for 45 seconds, mix it, and then microwave again for an additional 45 seconds. Set the chocolate aside to cool slightly after stirring until it develops a smooth consistency.
4. In the meantime, whisk the flour, cocoa, baking powder, and salt together in a medium mixing bowl.
5. The butter should be smoothed out using a hand mixer. After that, mix in the sugar until the mixture is frothy, then add the melted chocolate.
6. One after the other, beat in the eggs, make sure to do this well after each addition.
7. Beat in half of the flour mixture on low speed, then add in the sour cream mixture and the remaining flour mixture. Pour in the vanilla extract.
8. Snip off a corner of the large resealable plastic bag after pouring the batter into it. Afterwards, pipe the batter into the prepared cupcake liners. Bake the cupcakes for 14 to 15 minutes at 350°F; afterwards, leave them to cool fully.
9. Place the heavy cream in a microwave for 1 minute, or until it starts steaming; do this while the cupcakes are baking.
10. In a mixing dish, pour the steamed heavy cream over the chocolate and stir until the mixture gets smooth. Refrigerate this mixture for 15 minutes, or until cool enough to handle.
11. Using a medium-high speed mixer, beat until the mixture is thickened and has an excellent spreading consistency (this should last for about 5 minutes; the frosting will typically be the color of milk chocolate by this time).
12. Fill a piping bag with the frosting mixture and pipe it onto the tiny cupcakes with a little star tip (alternatively, you could spread the frosting onto the cupcakes).
13. Sprinkle chocolate sprinkles over the frosting for decoration.

This is an easy process for making mini cupcakes and the entire duration lasts for about 45 minutes, including a prep time of 15 minutes, a cook time of 15 minutes, and an extra 15-minute cooling period.

More ideas on how to bake mini cupcakes can be found in this video recipe.