Preheat the oven to 350 degrees. Line a cupcake pan with liners and set aside.

In a small bowl sift together the all-purpose flour, cocoa powder, espresso powder, baking powder, baking soda, and salt. Set aside.

Add the granulated white sugar and softened butter to a large bowl. Cream together with an electric mixer for 1-2 minutes.

Then add in the egg, egg yolk and vanilla and mix until pale in color and smooth, about 1 minute.

Next add in the sour cream and milk. Mix until combined.

Add the dry ingredients to the wet ingredients and combine.

Divide the batter between the 12 cupcake wells. Each should be ¾ of the way full. Bake the cupcakes for 17-19 minutes, or until a toothpick/cake tester comes out clean from the centers.

Let the cupcakes cool in the pan for 5 minutes then transfer to a cooling rack to cool completely.

Heat heavy cream just until boiling. (You can do this on the stovetop or microwave).

Add the semi-sweet chocolate chips or chopped chocolate to a bowl and pour the hot cream over top.

Let it sit for a minute, then stir to combine everything. Let the ganache cool to about room temperature before filling the cupcakes with it.

Transfer the ganache to a piping bag once it has cooled. It should be thicker but still easily worked with.

Add the hot cocoa mix and heavy cream to a microwave safe bowl. Microwave for 15-20 seconds. Stir to combine the cream and hot cocoa together. If the hot cocoa is not completely dissolved, microwave in 5 second intervals until it is. Let it cool to room temperature.

Add the butter and salt to a large bowl. Beat the butter with an electric mixer on high until it is super pale in color and fluffy, 5-7 minutes.

When the hot cocoa mixture is cooled to room temperature, add it and the powdered sugar a little at a time to the butter.

Lastly mix in the vanilla and cocoa powder.

Mix the frosting until it is light and fluffy, 1-2 more minutes.

Transfer the frosting to a piping bag fitted with a decorative tip. My favorite to use is my Wilton 1M tip.

Once the cupcakes are cooled, remove a bit of their centers. A cupcake corer is great for this.

Pipe a bit of chocolate ganache into the center of each cupcake.

Then pipe a generous amount of hot cocoa frosting onto the tops of each cupcake.

Store leftovers in an airtight container for up to three days.