Step 1: In a small bowl, sprinkle the unflavored gelatin powder over 1/2 cup of cold water. Let it sit for 5-10 minutes, or until the gelatin has bloomed and softened.
Step 2: While the gelatin is blooming, gently heat 1.5 cups of the berry puree in a saucepan over medium heat. Do not bring it to a rolling boil; just heat it until it's steamy and warm enough to dissolve the gelatin.
Step 3: Remove the warm berry puree from the heat. Add the bloomed gelatin mixture to the warm puree and stir continuously until the gelatin is completely dissolved. Ensure there are no grainy bits left.
Step 4: If using, stir in your desired natural sweetener (honey, maple syrup, or calorie-free alternative) at this stage. Taste and adjust to your preference.
Step 5: Pour the gelatin mixture into individual serving dishes, ramekins, or a larger glass container.
Step 6: Carefully transfer the dishes to the refrigerator. Chill for at least 4 hours, or preferably overnight, until the gelatin is firm and set.
Step 7: Once set, serve your delicious pink gelatin. Garnish with fresh berries or a sprig of mint, if desired.