Preheat your oven to 400°F (200°C). Roll out the puff pastry sheets and cut into desired shapes. Bake for 20-25 minutes until golden brown and puffed. Cool completely.

In a saucepan, combine mixed berries, granulated sugar, and cornstarch. Cook over medium heat for 5-8 minutes until thickened. Remove from heat and cool.

In a mixing bowl, beat heavy whipping cream with an electric mixer, gradually adding powdered sugar and vanilla extract until soft peaks form.

Layer the pastry on a serving platter, alternating with whipped cream and berry filling until all ingredients are used.

Cover and refrigerate for at least 30 minutes before serving.