Preheat oven to 350°F. Line 24 cupcake wells with liners.
Simmer the soda until reduced to ½ cup. Cool.
Cream butter and sugars. Add eggs, vanilla, and butter extract.
Stir in cooled butterbeer reduction and melted butterscotch chips.
Add flour mixture and buttermilk in batches. Mix until smooth.
Fill liners ⅔ full. Bake 14–18 minutes. Cool completely.
For frosting: beat butter until fluffy, mix in butterscotch, sugar, and extracts.
For ganache: melt chips and cream, then stir in honey.
Pipe frosting on cooled cupcakes. Drizzle with ganache.