Clean the cabbage leaves. Plunge them into a pan of salted boiling water, then let them blanch for 10 minutes. refresh and drain.
Cut the chicken breast in half lengthwise, flatten the resulting pieces. Melt 20 g of butter in a frying pan, add the chicken cutlets. season with salt and pepper, cook for 2 minutes on each side and set aside.
In the pan, sear the foie gras escalopes, salted and peppered, 30 seconds on each side; let cool.
Discard the fat from the pan and reduce the broth to three quarters. Add the Port, reduce by half. Incorporate the remaining butter, melting it gently, then the chopped truffle. Adjust the seasoning; keep warm.
Preheat the oven to th 7 (210°C). Crack the egg into a bowl and beat lightly with a little water for gilding.
Roll out the puff pastry and divide it into two rectangles. Place on each a half-leaf of cabbage and a chicken cutlet, then another half-leaf of cabbage and a slice of foie gras. Cover with a last half leaf of cabbage. Apply the egg wash to the free edges of the dough with a brush, then fold them over to envelop the filling.
Moisten a baking sheet, lay the puff pastries on it. Glaze the top with the rest of the egg. Put in the oven, cook for 15 minutes.
After 5 minutes of rest, arrange on plates.
Serve with the sauce and the rest of the reheated cabbage.
