for the chocolate cupcakes:

Cup of Yum
1. Preheat oven to 350° F. Line 2 regular size cupcake pans with 24 paper liners and set aside.
2. In a large bowl, whisk all dry ingredients to combine. Make 3 large holes in the dry ingredients. In a separate smaller bowl, combine oil and vinegar. Pour this into the 3 holes. Pour the water over entire mixture. Mix with a fork. Add vanilla and stir. Divide evenly into the 24 cupcake wells. Bake for about 25 minutes, or just until a toothpick comes out clean. Remove cupcakes to wire rack to cool completely.

for the pumpkin spice marshmallow filling:

1. In a medium bowl, stir together all ingredients until incorporated.

for the chocolate buttercream:

1. In a stand mixer fitted with a paddle, beat the butter until creamy. At low speed, beat in the powdered sugar. Increase the speed to high and beat until fluffy, scraping down the side of the bowl, about 2 minutes longer.
2. At low speed, beat in the cream, vanilla, cinnamon, and salt, then gradually beat in the cooled chocolate. Scrape down the side of the bowl and the paddle, increase the speed to medium-high and beat until light, 3 minutes longer. Using a wooden spoon, vigorously beat the buttercream for 30 seconds to deflate any air bubbles.

to assemble the cupcakes:

1. With a cupcake corer or a paring knife, cut a hole in the top center of each cupcake. Aim to cut about 1'' deep. If the hole is any deeper, the cupcake gets weak. Spoon the pumpkin spice marshmallow filling into a pastry bag fitted with a large plain tip (or use a sturdy plastic zip bag and snip off a corner.).
2. Pipe the marshmallow filling into each cupcake hole. Then spoon the chocolate buttercream into a pastry bag fitted with a large plain tip (I used Ateco No. 808) and swirl it on top of each cupcake. Finish with a dusting of cinnamon.