Prepare the Glasses: If you'd like, you can garnish the rim of your champagne flutes with a little sugar for an extra touch of elegance. Simply wet the rim with a piece of pineapple or water and dip it into granulated sugar.
Add Strawberry Puree: Spoon about 1 tablespoon (or more, depending on your preference) of the strawberry puree into each champagne flute.
Add Pineapple Juice: Pour about 2 ounces of pineapple juice into each glass over the strawberry puree.
Top with Champagne: Fill the rest of the glass with chilled champagne or sparkling wine. Pour slowly to prevent it from overflowing.
Garnish and Serve: Garnish with a fresh strawberry on the rim, a slice of pineapple, or a sprig of mint for a refreshing aroma. Serve immediately.