Preheat oven to 350 degrees.
In the bowl of a stand mixer or large mixing bowl combine the flour, cocoa powder, baking soda, salt and suger. Whisk to combine. In a small bowl add the milk, egg, canola oil and vanilla extract. Stir lightly and then add to the flour mixture. Beat until the ingredients are well combined and then add the warm coffee. Beat well, until the mixture is very smooth. Line a muffin tin with liners and using a 1/4 cup measure, add batter to each cup. Bake for 15-18 minutes. Let cool completely before frosting.
While the cupcakes bake make the frosting. Add 4 tablespoons butter to a small saucepan and heat over medium heat. Whisk constantly until brown bits appear on the bottom, about 5-6 minutes, then immediately remove from the heat and add the cream and brown sugar. Return to the heat and bring to a boil, boil for one minute. Remove from the heat and add to the bowl of a stand mixer. Stir in the vanilla bean seeds and allow to cool for 15 minutes. Once cooled beat in the remaining softened butter. Add the vanilla and powdered sugar to the bowl and beat together until well combined.
To make the popcorn. Preheat oven to 250°
Pour popped popcorn onto a parchment lined baking sheet.
Add butter to a small saucepan and heat over medium heat. Whisk constantly until brown bits appear on the bottom, about 5-6 minutes. Immediately remove from the heat and pour over the popped popcorn. Stir until evenly distributed. Sprinkle salt and brown sugar over the popcorn. Bake for 10 minutes. Baking helps the brown sugar and butter stick to the popcorn a litte better. Allow to cool before topping the cupcakes.
To assemble the cupcakes: Frost the cupcakes using a knife and a good amount of frosting. Add a handful popcorn to each cupcake and use your hands to mold it together into a mound, making sure to push the popcorn into the frosting. Some will fall off, just do your best to keep most of the popcorn on the cupcakes. Drizzle the melted chocolate overtop the popcorn and place the cupcakes in the freezer for 5 minutes or let sit on the counter for 30 minutes so the chocolate can harden. Then eat!! These are best the very same day you make them.