Mixed Berry Jam:

In a small saucepan, combine chopped berries and sugar over medium heat, stirring occasionally until berries break down and jam thickens, about 30 minutes.

Test the jam by spooning a small amount onto a plate. Cool slightly then stretch a glob of jam between your thumb and forefinger. If a strand forms, the jam is ready to use.

Spoon jam into a bowl. Stir in lemon juice and refrigerate until thickened and cold to the touch, about 1 hour.

Pastries:

Preheat oven to 205° C / 400° F. Line a half-sheet baking tray with parchment or a silicone mat.

On a silicone rolling mat or lightly floured countertop, unroll one sheet of puff pastry. Use a rolling pin to roll the pastry a few inches longer, or a knife to trim away any excess, forming a rectangle about 8 x 12 inches in size.

With a sharp chef’s knife, slice the rectangle into 6 squares, about 4 x 4 inches in size.

Arrange on prepared tray.

Repeat with the second sheet of pastry.

Spoon jam, dividing it equally between the 6 squares.

With a pastry brush, brush a thin strip of beaten egg around the edges of each square.

Top with the remaining 6 squares of pastry. Seal the edges with your fingertips.

Crimp the edges of each square with a fork.

With a pastry brush, brush the tops of the squares with the beaten egg.

Bake in preheated oven for 25 minutes, or until flaky and deeply golden brown.

With a flat spatula, transfer pastries to a wire rack. Set aside to cool while you prepare the glaze.

Vanilla Bean Glaze:

In a small bowl, whisk together confectioner’s sugar, milk, vanilla bean paste, and food coloring.

Spoon glaze over pastries.

Serve immediately. Store leftovers in an airtight container at room temperature for up to one day.