Step 1

Heat the olive oil in a pan, then add the onion and cook gently for 20-30 minutes or until caramelised.

Step 2

Put the cut sweetpotatoes into boiling water and cook for 3 minutes, then drain in a large colander.

Step 3

Preheat the oven to 180°C.

Step 4

Unroll the pastry and gently roll it to make it square-shaped.

Step 5

Lay a plate approximately 28 cm on top of the pastry and cut around.

Step 6

Put the pastry on a non-stick baking tray.

Step 7

Spread the onion over the pastry, leaving a 2 cm border.

Step 8

Slice the brie, then put it on top of the onion, then lay it over the sweetpotatoes in a neat overlapping pattern.

Step 9

Brush with a little more olive oil, then season all over.

Step 10

Fold the border back over the edges of the sweetpotatoes.

Step 11

Sprinkle the frozen cranberries and some fresh thyme.

Step 12

Brush the pastry with the beaten egg, then cook for 40-45 minutes or until the pastry is crisp and golden.

Step 13

Serve with cranberry sauce.