Preheat oven to 350.

In a mixer, cream butter until light and fluffy.

In the microwave or in a double broiler, melt the 3 oz of chocolate until smooth. Sprinkle in the espresso powder and add to the butter; mix until combined.

In a smaller bowl, combine eggs, brown sugar, and vanilla extract. Once mixed, add to the butter/chocolate mixture and mix together.

In a large bowl, sift the flour, cocoa powder, baking powder, baking soda, and salt together.

Lastly, in small bowl, combine the heavy cream, greek yogurt, and coffee.

Alternately, add the flour and milk mixture to the butter mixture. Stir until just combined.

Divide into 12 muffin cups, and bake for 18-22 minutes or until a cake tester comes out clean.

Beat butter and peanut butter until light and fluffy. Add in vanilla and salt. Beat together.

A cup at a time, slowly add in powdered sugar. I used about 2 1/4 cups, but use as little or as much as you want to reach your desired frosting taste/consistency.

Similarly, add in heavy cream a Tbsp at a time until your frosting has reached your desired consistency (the heavy cream gives the frosting a smooth finish, and the more you beat the frosting with the heavy cream, the fluffier the frosting is).

With a knife, cut a small hole in the center of each cupcake, about a 1/4 of the way down into the cupcake. Place 3-4 marshmallows inside. Cover with frosting (a great way to use the extra cake is to make cake balls).

For the drizzle, melt the chocolate until it is smooth. In a plastic bag with the tip cut off (a makeshift piping bag) drizzle the chocolate over the frosting.

Enjoy!