1. Preheat oven to 300º F.
2. Coat four small ramekins with butter and set aside.
3. In a large bowl, whisk together the flour, baking soda, cocoa powder, and salt and set aside.
4. In a stand mixer fitted with a paddle attachment, combine the butter and sugar until light and fluffy. Scrape down the sides of your bowl.
5. Add egg and vanilla and continue to mix until combined.
6. With the mixer on low, add the buttermilk, scraping down the sides of the bowl as needed.
7. Beginning and ending with the flour mixture, alternate between adding the flour mixture and the coffee to the batter with the mixer on low. Mix just until combined and scrape down the sides of the bowl.
8. Using a 1 tbsp cookie scoop, carefully scoop about four scoops into each ramekin to ensure they are all even.
9. Bake for 22-25 minutes until a toothpick inserted in the center comes out clean.
10. Cool for 10 minutes on a cooling rack.
11. Gently run a knife along the edges of each cake before carefully turning them out of their ramekins. Let cakes cool on rack until completely cool.

Chocolate Frosting

1. Heat bittersweet chocolate in a double boiler or in the microwave, stirring it until it melts.
2. Using a stand or handheld mixer, beat the butter on medium-high speed for 2-3 minutes until light and fluffy.
3. With the mixer on low, slowly add in spoonfuls of the powdered sugar mixture.
4. Scrape down the sides of the bowl as needed and mix until light and fluffy.
5. Add in the melted chocolate and mixing just until combined.
6. Chill frosting until needed.

Assembly

1. Once cakes have completely cooled, use a serrated knife to gently cut off their domed tops so you have four cake layers.
2. Scoop the chocolate frosting into a pastry bag fitted with a large piping tip. I used an Ateco 869, but any large piping tip will work.
3. Place one cake layer in front of you. While holding the piping bag vertically above the edge of the cake, pipe downwards, pushing down right before releasing.
4. Continue to pipe four dollops of frosting around the outer edge of the cake, followed by one right in the center.
5. Place one raspberry in between each of the four dollops of frosting on the outer edge so that there are now four raspberries gently nestled into the frosting.
6. Repeat this process with the other three cakes.
7. Carefully pipe a swirl on top of two of the cakes, as close to the center as possible. Place the other cake layers on top of each of those with the extra frosting, gently press down to ensure it adheres to the frosting underneath it and is level.
8. Enjoy!