Preheat oven to 350°F (175°C). Line 24 mini tart pans with mini cupcake liners.
Combine graham cracker crumbs, 2 tablespoons sugar, and melted butter in a bowl. Press 1/2 tsp of mixture into each tart.
In a separate bowl, mix cream cheese and sour cream until smooth.
Add melted white chocolate and 1/2 cup powdered sugar to the cream cheese mixture. Stir in vanilla extract.
Spoon a small amount of the mixture into each tart to cover the crust (about 1 tsp per tart).
Bake for 9 minutes. Let cool completely before placing in freezer.
In a saucepan, combine 1/4 cup water, 2 tablespoons sugar, 1 tablespoon cornstarch, lemon juice, and huckleberries. Cook until thickened, about 5 minutes.
Add remaining 1 tablespoon cornstarch to the saucepan and stir an additional 2 minutes until glossy and thick.
Remove cheesecakes from freezer. Spoon 1/4 cup of berry topping into each tart.
Chill cheesecakes for 1 hour. Whisk whipping cream and 1 tablespoon sugar until stiff peaks form. Pipe whipped topping over tarts and garnish with remaining crumb mixture.
Freeze until serving, up to 2 hours.