Roll out the sheet of puff pastry to 40cm x 15cm and p***k it with a fork. Place it onto a sheet of parchment paper, slide it onto a baking sheet and transfer to the fridge to chill. Meanwhile cut the endive heads in half lengthways, score the root end in a criss cross fashion and set aside. Place a large heavy-based pan over a medium heat, leave for two minutes, add the vegetable oil and a sprinkling of salt. Add the chicory, flat surface down and cook until you have achieved a golden colour on the underside.
Turn the chicory over, add the butter, sprinkle the upper surface with the demerara sugar and Nespresso Cosi grounds and leave the underside to colour for a minute or two. Turn the chicory back over, cook for a further minute or two, then add the orange juice and cook until it has reduced to a syrupy consistency. Lift them out and set aside to cool, reserving any buttery juices from the pan. Lay the chicory halves neatly onto the length of pastry and set aside until required. Place the caster sugar into a heavy-based pan, place it over a high heat and cook until you have achieved a rich golden caramel. Add the vinegar, let it froth up and boil away for 30 seconds and add the cherries. Cook until the cherries have released all of their juice and the excess moisture has evaporated. Drain the cherries in a colander, transfer them to a blender and blend to a smooth puree then set aside. Reserve the juices.
Place the tarte fine into an oven pre-heated to 200ºC and bake for 20 minutes or until a rich golden brown colour is achieved and the pastry is crisp. Remove from the oven, and use a pastry brush to glaze the endives with some of the buttery juices left in the pan in which they were caramelised. Set aside in a warm place and turn the oven down to 160 degrees C.
Score the skin of the duck breast with a sharp knife ensuring you do not go too deeply and penetrate the meat. Sprinkle the surface of a large oven proof pan with salt, add the breasts skin side down and place over a medium heat. Cook until the skin is a golden colour, tipping out any excess fat if required. Transfer the pan to the oven and cook the breasts for 8 minutes.
Remove from the oven, take the breast out of the pan, tip out any excess fat, add the chicken stock to the pan, along with the cherry juices and reduce to a coating consistency sauce then set aside. Warm up the cherry puree.
TO SERVE
Carve the duck into thin slices, cut the tarte into 10 even slices and serve on pre-heated plates with some cherry puree and sauce.