Add the white rum, coconut liqueur, and pineapple juice to a cocktail shaker filled with ice.
Shake vigorously for 10–12 seconds until well chilled.
Strain into a chilled coupe or large wine glass.
Top with prosecco, pouring gently over the back of a bar spoon to preserve the bubbles.
Garnish with a small skewer or cluster of fresh blueberries rested on the rim.
A margarita glass is a poor choice for a sparkling cocktail - its wide, shallow bowl accelerates carbonation loss and makes the prosecco topping difficult to control. A coupe or large wine glass preserves the bubbles and better showcases the layered pour.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Bounty Hunter.