In a small bowl, add the blueberries, strawberries, lemon zest and juice, vanilla, cornstarch and granulated sugar. Toss with a spoon.
1 cup fresh blueberries, ⅓ cup fresh strawberries, 1 lemon, ¼ cup granulated sugar, ½ tsp vanilla extract, 1 tsp cornstarch
Lightly flour a work surface. Unroll your puff pastry sheet - it should be cold but not frozen solid. Use the rolling pin to roll it out to ¼ inch thick. Slice the pastry into six even rectangles.
1 sheet puff pastry, flour
Preheat the oven to 400℉. Line a baking sheet with parchment paper and space out the puff pastry rectangles.
Add a slice of brie to the center of each tart. Top with a hefty spoonful of the berry mixture, leaving a small border around all edges.
6 slices brie cheese
Dab some cream on the puff pastry edges to help them stick. With your hands, fold the sides of the pastry over to seal the tarts on all edges.
2 tbsp heavy cream
Brush the egg wash on exposed pastry so that it browns in the oven. Place the tarts in the center of the oven and bake for 20 minutes. Remove and let cool for 5-10 minutes. Enjoy with a scoop of ice cream!