Lightly spray an 8” x 4” loaf pan with cooking spray.
In a bowl, toss berries gently to combine.
In another bowl using an electric mixer, whip cream until soft peaks form. Fold in whipped topping.
In a saucepan, sprinkle Splenda Sweetener and gelatin over water in a small saucepan; let stand 1 minute. Cook over low heat, stirring until gelatin dissolves (about 2 minutes). Stir in vanilla extract.
Place saucepan in a bowl of ice water to cool; stir with a rubber spatula until mixture is the consistency of unbeaten egg white.
Quickly stir gelatin into whipped cream; fold to combine well. Add cream mixture to berries and toss gently to coat.
Transfer mixture to prepared loaf pan; cover and refrigerate for 1 hour or until set.
Unmold onto a cutting board and slice into 8 servings. Garnish with mint leaves if desired.