Preheat oven to 350 degrees. Line cupcake pans with paper liners.

In heat proof bowl, pour coffee over cocoa and chopped chocolate. Let sit for 2-3 minutes, then whisk together. Set aside.

In mixing bowl, whisk together flour, baking soda, and salt. Once mixed, add in chocolate/coffee mixture, oil, sugar, vanilla, buttermilk, and eggs. Beat until combined. Batter will be very thin. Do not over mix.

Fill cupcake lines 2/3 full. Bake for 18-20 minutes until toothpick comes out with just a few crumbs. Do not over bake.

Place Milka Oreo candy bar and chocolate chips in a heat proof bowl.

Put heavy cream in a microwave safe dish and microwave on high until cream starts to boil, about 45 seconds.

Pour heavy cream over chocolate & candy and cover bowl with plastic wrap. Let sit for 5 minutes.

After 5 minutes, whisk until smooth and let sit for 2-3 minutes before using.

Melt Milka Oreo bars in small pot on stove over low heat. Stir frequently. Once melted, remove from heat to cool.

Use mixer to beat butter until light and fluffy, about 5 minutes.

Beat in powdered sugar 1/2 cup a time, scraping down sides as needed.

Add vanilla and salt.

Mix in cooled candy bars.

Mix in cream, 1 tablespoon at a time, until desired consistency reached.

Remove centers of cupcake. I use this cupcake corer (Amazon affiliate link) from Wilton, but you can also use a small spoon or knife to core out a 3/4 inch area about 1/2 down through the cupcake.

Fill cupcake centers with ganache.

Top cupcakes with frosting.

If desired, grate bar, and dust over cupcakes.