Pre-heat oven to "400 degrees F". Line a large baking sheet with parchment paper. Melt butter in a small pan;add the shallots, garlic and rosemary season with salt and pepper and sauté until softened. Set aside to cool.In a large bowl,combine the shallot and add the remaining filling ingredients .Gently mix together and set aside.Meanwhile on a lightly floured work surface, roll out the puffed pastry to a 54 cm x 22 cm rectangle .Lay the filling in the center length of the pastry.Fold the pastry over on both ends to enclose the filling and roll over so the seal is underneath,place on a prepared baking sheet.Brush the roll with egg wash.

To prepare the topping: in a bowl of a food processor combine rosemary,walnuts,salt,salt and piment d'espelette,Process using on-off pulses to a fine dice. Sprinkle over sausage roll. Make 4-5 slits in the top of the roll.Lower heat to 375 degrees F.Place foIl loosely over sausage roll and bake for 55-60 minutes. Remove foil 5 minutes before end of cooking time.

Meanwhile prepare grape sauce. In a skillet heat the olive oil.Add the grapes and sauté,shaking the pan for about two minutes until the start to colour. Lower the heat to medium, add the sugar,rosemary and pimento d'Espelette. Shake the pan to distribute evenly. As the usage starts to caramelize, add the grape must, turn the heat down to low and cook for a further 5 minutes. Slice the sausage roll and serve with grape sauce and lava puree.