Place 2 cookies in the bottom of each mini dessert container. For a softer texture, quickly dip the cookies in milk before layering. If you prefer a little more texture, add them as-is.
Spread a layer of Cool Whip over the cookies. Top with a few strawberries and blueberries, then drizzle with mixed berry syrup.
Add 2 more cookies on top of the berry layer, dipping them in milk first if desired. Spread another layer of Cool Whip over the cookies.
Finish with patriotic sprinkles and a few extra berries, if desired.
Cover and refrigerate for at least 8 hours or overnight. As the desserts chill, the cookies soften into cake-like layers that give these icebox cakes their signature texture.