Preheat the oven to 350 °F.
Crush the pretzel thins until a uniform, coarse crumb is reached.
Melt the butter, the stir the crushed pretzels, brown sugar, and vanilla extract into the melted butter.
Pack the pretzel mixture into the base of a 9 x 13 baking dish.
Bake the pretzel crust for 10 minutes until carmelized.
Allow the pretzel crust to cool completely.
While the pretzel crust cools, whip together the cool whip, cream cheese, and sugar until smooth.
Spread the cream layer evenly over the cooled pretzel crust.
Sprinkle blueberries over the cream layer, lightly pressing them into the cream to keep them from rolling around.
Allow the preztel and cream layers to cool in the refigerator while the gelatin layer is prepared.
Pour the raspberry gelatin powder into a heat-safe bowl, and top with the boiling water. Whisk until the gelatin has dissolved completely.
Allow the gelatin liquid to cool to room temperature, about 1 hour.
Slowly pour the raspberry gelatin over the cream layer, taking care to keep the layers separate.
Cover, then chill in the refrigerator at least 4 hours, or overnight.
Slice into squares and serve.