Preheat your oven to 200°C (390°F) and line a baking sheet with parchment paper.
Unroll the puff pastry sheet and cut it into 24 small squares, roughly 3x3 inches each. Arrange them evenly on the prepared baking sheet.
Bake the pastry squares for about 10 minutes, or until they are lightly golden and puffed. Remove from the oven and let them cool slightly on a wire rack.
While the pastry cools, place cranberries, sugar, and orange juice in a small saucepan over medium heat. Stir gently and cook for about 5 minutes, until the cranberries burst and the mixture thickens into a jammy sauce with a bright aroma.
Slice the brie into tiny cubes or thin slices. Top each cooled pastry square with a piece of brie, pressing gently so it stays in place.
Using a spoon, dollop a small amount of the cranberry sauce over the brie on each pastry. The sauce should be glossy and slightly thickened.
Brush the edges of each pastry square with the beaten egg to give a shiny, golden finish once baked.
Return the assembled bites to the oven and bake for another 8-10 minutes, or until the pastry is golden and puffed, the cheese is bubbling, and the cranberry topping is glossy.
Remove from the oven and let the bites cool for about 5 minutes. They should be warm, crispy on the edges, and melty in the center.
Serve these bites slightly warm or at room temperature, enjoying the flaky crust, creamy cheese, and vibrant cranberries in every bite.