Preheat the oven to 200oC, gas mark 6. Line a large baking tray with baking parchment.
Open the croissant dough can according to the pack instructions and cut along the perforated lines to make 6 triangles.
Spread each triangle with cranberry sauce. Sprinkle 75g walnuts over the dough. Place the Brie at the short edge of the dough and roll to the opposite corner to form a croissant shape, transfer to the baking tray.
Brush with egg and sprinkle over the reserved walnuts. Bake for 15-18 minutes until golden. Serve warm.
Notes
Cooks tip Try replacing the brie with grated Gruyere.