01 - Preheat the oven to 350°F. Line a muffin tin with twelve paper cupcake liners.
02 - Whisk together flour, cocoa powder, baking powder, baking soda, and salt in a medium mixing bowl until evenly blended.
03 - In a large bowl, use an electric mixer to cream the butter with sugar until pale and airy. Incorporate the eggs individually, then blend in vanilla extract.
04 - Add half of the dry mixture to the creamed butter and sugar. Pour in the milk and sour cream, mix gently, then fold in the remaining dry ingredients until just combined.
05 - Evenly distribute batter among prepared liners. Bake for 18 to 20 minutes, or until a tester inserted comes out clean. Allow cupcakes to cool completely in the tin.
06 - After cupcakes are cooled, use a corer or small knife to remove a one-inch plug from the center of each. Fill cavity with mini candy-coated chocolates and replace the tops.
07 - Beat softened butter in a mixing bowl. Gradually add powdered sugar, cocoa powder, milk, and vanilla, whipping to a smooth, fluffy consistency.
08 - Generously frost each cupcake with icing, shaping it into a mound high enough to hold the witch hat decoration.
09 - Melt chocolate chips in a heatproof bowl set over simmering water or microwave in short bursts until smooth. Dip each sugar cone in melted chocolate, letting excess drip off. Decorate the wet chocolate with colored sugar or sprinkles.
10 - Place a chocolate wafer cookie onto each frosted cupcake. Stand a chocolate-dipped cone upright on top of the cookie. If desired, wrap a candy belt or licorice strip around the cone base to resemble a hat band. Allow the chocolate to firm before serving.