There are a number of different drinks with the name 'Imperial Punch', but this version comes from the CocktailDB - an invaluable resource when you have leftover ingredients and want to figure out what to do with them.
1.5 oz bourbon
0.5 oz lemon juice
0.5 oz orange liqueur
Build over ice in a tall glass and top with sparkling wine, then stir briefly to mix the ingredients.
The nose has subdued notes of prosecco with a hint of bourbon barrel and orange. The sip is initial crisp, from the prosecco and lemon, which is briefly smooth and sweet, then dries out again, finishing with the sparkling wine and bourbon.
This is a nice medium weight drink. The bourbon gives it a little heft, but lengthening it with sparkling wine keeps it from being too heavy. Just keep in mind that you're drinking something that's mostly made of booze, so it can sneak up on you. Especially true if you're like me an prefer to make bourbon cocktails with 100+ proof whiskey. I went with Weller Antique 107, which makes for a very smooth drink, but a spicier bourbon like Old Grand Dad 114 could definitely give it a bit more pep.