The idea of this recipe came from the very thin apple tarts that are served in some restaurants for dessert. I love puff pastry and thought that warm sweet potato and cheese would be brilliant on puff pastry as a first course or as an hors d'oeuvre. I chose Saint-Andre Cheese because it's very similar to Brie but with a more buttery texture and melts very well. Serve ithe tarts warm with salad as a first course (or make a big tart either round or rectangular and cut in pieces). You can make ahead and just put the tarts in the oven at the last minute to melt the cheese and re-warm the potato and puff pastry. I used pre-rolled puff pastry sheets, rolled to 1/4 inch thickness and used a 4.5 inch plate to cut around and have all circles the same size. —Maria Teresa Jorge
Pre-heat the oven to 400 degrees F. with rack in the middle.
Put a pot of water with a dash of salt over high heat and bring to the boil.
Using a mandoline cut your potatoes in chips medium thin. Blanch your chips in the boiling water for 1 minute, strain, cool under cold water to stop further cooking and put on a clean kitchen tea towel.
Line a baking sheet with parchment paper, lightly smear it with olive oil (preferably garlic infused - see my recipe posted). Using the blanched chips, make a circle overlapping them so you obtain a disk at leats 1/2 an inch smaller then the pastry you cut. Drizzle some olive oil on top, sprinkle with salt, freshly ground pepper and fresh thyme. Make 6 potato crowns. Bake in the oven for 10 minutes to dry out the potatoes.
Open your puff pastry and if it's thick roll it out so you get to 1/4 inch thickness. You really want these tarts to be extra thin. Roll out the puff pastry between 2 sheets of parchment paper (if you roll out dusting the pastry with flour the puff pastry will end up heavier because it will absorb all the flour).
Remove the top parchment sheet, cut 6 equal circles of 4.5 inch diameter - I used a plate to cut around (or cut in square or rectangle, whichever you prefer).
Important note: always use a very sharp knife to cut the puff pastry and cut down sharply rather then a pulling motion with the knife. You want the pastry to be cut through vertically so it puffs, if you pull it, the layers will stick together and won't puff up.
Cover the puff pastry with the top parchment sheet and chill until you need it.
Cut up the cheese in little cubes and divide in 6 equal portions.
Put the puff pastry disks in a baking sheet lined with the parchment paper you used to roll out the dough. With a wide thin spatula, transfer the roasted sweet potato crowns and put them in the middle of the puff pastry. Put the oven rack one up and bake the puff pastry tarts with the potatoes in the oven until the puff pastry has risen and both the potatoes and the pastry are golden.
Divide the cheese on the 6 puff pastries and potato tarts, put back in the oven until cheese has just melted.
Serve immediately with fresh green and red autumn salad leaves seasoned with some vinaigrette. If you have guests that don't eat cheese, you can serve it just with the sweet potato like one of the photos I uploaded.
If making ahead, stop at step 10 and only finish with the cheese when you are ready to serve.