An all-American favorite gets a twist with the addition of Kentucky bourbon and Limoncello.
Mix Limoncello, lemon juice, bourbon, grenadine syrup, brown sugar and vanilla in cocktail shaker with muddler or wooden spoon until brown sugar is dissolved. Add 2 cups ice cubes; shake until well mixed and chilled.
To serve, strain over ice cubes in beverage glasses. Fill glasses with seltzer. Garnish with lemon slices.