1. Preheat oven to 350°.
2. To prepare cupcakes, weigh or lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, cocoa, baking soda, and 1/8 teaspoon salt, stirring with a whisk.
3. Place 3/4 cup sugar and 1/4 cup butter in a large bowl; beat with a mixer at medium speed until well combined (about 3 minutes). Add eggs and vanilla, beating well. Add flour mixture and buttermilk alternately to egg mixture, beginning and ending with flour mixture. Fold in chocolate. Spoon batter into 12 muffin cups lined with muffin cup liners. Bake at 350° for 18 minutes or until a wooden pick inserted in center comes out with moist crumbs clinging. Remove from pan; cool completely on a wire rack.
4. To prepare icing, combine 1/2 cup brown sugar and bourbon in a saucepan; bring to a boil. Cook, without stirring, for 3 minutes or until a candy thermometer registers 250°. Combine egg whites, cream of tartar, and 1/8 teaspoon salt in a large bowl; using clean, dry beaters, beat with a mixer at high speed until foamy. Pour hot sugar syrup in a thin stream over egg whites, beating at high speed until stiff peaks form, about 3 minutes. Reduce mixer speed to low, and continue beating until the egg white mixture cools (about 3 minutes).
5. Place 1/4 cup butter in a large bowl; beat until light and fluffy. Fold in 1 cup egg white mixture. Fold butter mixture into the remaining egg white mixture. Spread about 3 tablespoons icing over each cooled cupcake. Combine meringue powder and 1 tablespoon water in a bowl, stirring with a whisk until smooth. Add powdered sugar, beating with a mixer at medium speed until thick and smooth. Stir in black food coloring to desired shade. Scrape the powdered sugar mixture into a zip-top plastic bag, and snip a tiny hole in 1 corner of bag. Pipe black spiders or webs over frosted cupcakes.