In a medium saucepan, gently combine the raspberries, water, and sweetener. Bring this mixture to a light simmer over medium heat, cooking for about 5 minutes until the berries are wonderfully soft and easy to mash.
Remove the saucepan from the heat. Carefully pour the berry mixture through a fine-mesh sieve, pressing firmly on the berry solids to extract all the delicious, vibrant juice and leave the seeds behind. Set the syrup aside to cool.
Grab a tall glass and fill it generously with ice. Pour in your preferred club soda or sparkling water, leaving about two inches of space from the rim.
Stir in ΒΌ cup of your freshly made raspberry syrup. For that classic creamy finish, gently swirl in one tablespoon of heavy cream.
For an extra flourish, you can top your soda with a dollop of lightly sweetened whipped cream and a fresh berry. Sip and savor your refreshing, healthy treat!