Heat the oven to 375°F (190°C). Lightly grease a 24-cup mini muffin pan.
Unfold the thawed puff pastry and roll it gently to smooth the creases. Cut it into 24 even squares.
Press one square into each muffin cup, leaving the corners visible above the rim.
Put a small cube of cold Brie into each pastry cup. Add a small spoonful of cranberry sauce on top.
Bake for 15–18 minutes, until the pastry is puffed and deeply golden at the edges and the cheese has melted.
Leave the bites in the pan for about 5 minutes. Lift them out carefully and serve warm.
