1 ounce Buffalo Trace bourbon
1/2 ounce Carpano Antica vermouth
1/4 ounce fresh lemon juice
1/4 ounce agave syrup
4 ounces kölsch or similar light lager-style beer
Lemon slice, for garnish
Combine bourbon, vermouth, lemon juice, and agave syrup in a Belgian-style beer glass; stir. Fill with ice and top with kölsch. Garnish with lemon slice.