Preheat the oven to 375 degrees and line two baking sheets with parchment paper.

In a medium bowl add the flour, baking powder, cinnamon, and salt. In a mixer fitted with the paddle attachment, beat the butter, and brown sugar until light and creamy, about 3 minutes. Add the eggs, buttermilk, and vanilla and beat until well incorporated.

In a small bowl, combine the milk, baking soda and vinegar. Add this mixture to the batter along with the flour mixture and beat on low speed until completely combined.

Put the batter into a pastry bag fitted with a large round tip, you can also use a ziploc back and just cut off one tip, and drop about 1 tablespoon of batter onto the baking sheet. Repeat making sure to leave about 2 inches in between the cakes.

Bake for about 10-12 minutes until the cakes begin to brown. Remove from the oven and let the cakes cool on the baking sheet for 3-5 min before transferring them to a rack to cool completely. Let them cool for a couple minutes on the baking sheet before moving them.

To make the marshmallow cream, beat the marshmallow fluff and butter (you can also use shortening) in a mixer, starting on low, then gradually increasing the speed to medium until the mixture is smooth and fluffy. Reduce the speed to low and add the powdered sugar and vanilla and mix well. Increase the speed to medium again until mixture is fluffy. Place the marshmallow cream into a piping bag or another ziploc bag.

In a sauce pan heat the cream over medium heat until it starts bubbling. In a heat proof bowl add the chocolate. Pour the hot cream over the chocolate and let it sit for 10 minutes until the chocolate melts. Whisk the chocolate and cream together until it’s nice and smooth. You need to let the chocolate ganache rest at room temperature so that it firms enough to spread, about 2 hours, or do what I did and place it in the freezer to speed up the process.

Pair the cakes up with cakes of similar size and turn them over with the flat side up. On half of the cakes, pipe the marshmallow cream.

On the other half, pipe the cooled chocolate ganache.

Bring the two cakes together, but do not squeeze. You may store them in the fridge in an air tight container.