In a medium bowl, whisk together the instant vanilla pudding mix and milk. Stir until the pudding mix has dissolved and the mixture thickens, which should take about 2 minutes.
2. Combine with Sour Cream/Yogurt:
Add the sour cream (or Greek yogurt) to the pudding mixture and stir until smooth and fully combined. This adds creaminess and a slight tang to balance the sweetness.
3. Fold in Whipped Topping:
Gently fold in the whipped topping (Cool Whip) until the mixture is smooth and fluffy.
4. Add Blueberries and Marshmallows:
Carefully fold in the fresh blueberries and mini marshmallows. Be gentle to keep the blueberries intact for that burst of freshness.
5. Chill:
Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or preferably overnight, to let the flavors meld and for the salad to chill thoroughly.
6. Serve:
Before serving, garnish with chopped nuts (if using) or extra blueberries for decoration. Serve chilled and enjoy!
