Step 1: Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners.
Step 2: In a small saucepan, combine the milk and the minced ghost pepper. Heat over low for 5 minutes (do not boil) to infuse, then remove from heat and let cool to room temperature.
Step 3: In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Step 4: In a separate bowl, whisk the eggs, oil, sour cream, vanilla, and the cooled, infused milk (strain out the peppers if you want less heat).
Step 5: Gradually add the wet ingredients to the dry ingredients, stirring until just combined and no large lumps remain.
Step 6: Divide the batter evenly among the muffin cups, filling each about two-thirds full.
Step 7: Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Cool completely on a wire rack.
Step 8: For the frosting, heat the heavy cream until simmering, pour over chopped dark chocolate, let sit for 5 minutes, then stir until smooth and glossy. Let thicken before frosting cupcakes.