Preheat the oven to 350. Line 6 holes on a standard sized cupcake tin with paper liners.
In a food processor pulse the cake ingredients until smooth. Divide between the prepared cupcake liners.
Bake for 26-28 minutes or until the cupcakes no longer jiggle and feel firm when lightly pressed. Cool completely.
Meanwhile, in a small bowl, stir together the ingredients for the buttercream. Set aside.
In a separate small bowl microwave the heavy cream and peppermint extract until hot but not boiling, about 2 minutes. Add the chocolate chips and stir until they are melted. To get a very smooth, thick ganache transfer to a small blender and blend until thickened and glossy.
To assemble: cut a small piece from the centers of the cupcakes. Divide the buttercream between them. Put the piece of cake you removed back on top. Spread the ganache over the cupcakes.