Preheat the oven to 180°C (350°F). Line a 12-cup muffin tin with paper liners.
In a large mixing bowl, beat the butter and sugar together until light and fluffy.
Beat in the eggs one at a time, then mix in the vanilla extract.
Combine the dry ingredients: In a separate bowl, sift together the flour, cocoa powder, and baking powder.
Add the dry ingredients to the wet mixture in two additions, alternating with the milk. Stir gently until the batter becomes smooth and lump-free.
Divide the batter evenly among the liners, filling each about three-quarters full. Bake for 25 minutes, or until a toothpick inserted in the center comes out clean.
Remove from the oven and transfer the cupcakes to a wire rack. Let them cool for at least 40 minutes before decorating.
Prepare the chocolate ganache: Place the chopped dark chocolate in a heatproof bowl. Pour the hot cream over it, let sit for one minute, then stir until the chocolate melts and becomes glossy.
Dip each cooled cupcake into the ganache.
Spider Webs: Pipe white chocolate in circles, then drag a toothpick outward to form a web.
Owls: Use Oreo halves for eyes and M&Ms for pupils.
Devils: Shape horns from red fondant.
Graves: Add a small cookie “tombstone” and write “RIP” with melted white chocolate.