Pre heat your oven to 220°C (200°C (fan), gas mark 7).
Roll out the stuffing as thin as possible between 2 pieces of baking paper.
Remove the top piece of baking paper and place 3 cabbage-wrapped partridge breasts on top of the stuffing strip and then cover with another strip. Repeat the process until you have 3 layers.
Roll the layered partridge and stuffing in baking paper to create a cylinder shape. Remove the baking paper.
Take the puff pastry sheet and place the Wellington filling in the centre.
Egg-wash the pastry around the filling and then seal the pastry. Ensure there is a 2cm overlap (trim any excess pastry before sealing).
Turn the Wellington over so the seal is on the underside.
Trim any excess pastry at the ends and tuck underneath.
Decorate with a pastry lattice if desired and chill for 15 minutes before egg washing.
Place in the oven on a heavy baking tray for 30-40 minutes.
Turn every 10 minutes and probe to a core temperature of 45°C.
Remove from the oven and rest on a cooling rack for 30 minutes. Once rested, carve and serve.