Crush chocolate sandwich cookies until fine crumbs. Mix with melted unsalted butter and press into a 9x13 inch dish. Freeze for 15 minutes.

In a bowl, beat cream cheese, powdered sugar, and vanilla extract until smooth. Spread over the chilled crust.

In a saucepan, combine strawberries, granulated sugar, and cornstarch. Cook until thickened, then cool and spread over the cream layer.

In another saucepan, repeat the process with blueberries, sugar, and cornstarch. Cool and pour over the strawberry layer.

Whip heavy cream and powdered sugar until firm peaks form. Spread or pipe over the dessert, and add star sprinkles if desired. Chill for at least 2 hours.

Slice with a hot knife and serve chilled.