01 - In a cocktail shaker or sturdy glass, muddle together the raspberries, mint leaves, lime wedges, and simple syrup until the berries are crushed and the mint aroma is released.
02 - Add the white rum (if using), lemon-lime soda, and sparkling water; stir well to combine.
03 - Fill two tall glasses with a scoop of vanilla ice cream each.
04 - Strain the raspberry-mint mixture evenly over the ice cream in both glasses.
05 - Gently stir to marble the flavors. Garnish with extra mint leaves and fresh raspberries. Serve immediately with straws and spoons.