Combine Splenda Granulated Sweetener and water in a small saucepan over medium heat. Stir until sweetener dissolves. Remove from heat and refrigerate until chilled, about 30 minutes.
Fill a cocktail shaker halfway with ice. Add 1 ½ ounces sweetener mixture, gin, and lemon juice. Cover and shake until well chilled.
Strain into chilled Tom Collins glass filled halfway with ice. Top off with club soda. Garnish with a lemon wheel and maraschino cherry. Refrigerate the remaining sweetener mixture in an airtight container.