In a saucepan over medium-high heat, bring blueberries and cream soda to a boil. Reduce to a simmer. Stir until the blueberries have burst and the syrup has thickened, about 5 minutes. Remove from heat and cool. Strain and discard solids. Syrup can be stored in the refrigerator in a sealed container, for up to one week.
Place the rum, 3 tablespoons blueberry cream syrup and Chai tea in a cocktail shaker. Add ice and shake well.Strain into two cocktail glasses with ice. Top with a splash of cream soda.Garnish with additional blueberries if desired.
