In a medium non-stick pan, heat the olive oil over medium heat. Add the potato slices in a single layer, add the cumin, paprika, thyme and parsley and fry about 4 minutes on each side or until tender.
With a slotted spoon, transfer the potatoes to a plate lined with paper towel and set aside. Add the onions and mushrooms to the pan and cook for about 10 minutes or until caramelized.
Preheat the oven to 400 F.
Line a baking sheet with parchment paper. Place the puff pastry on the baking sheet. Spread the potatoes, mushrooms and onions on top of the pastry, leaving about 1 inch border.
Top with the brie the cheese. Season with salt and pepper. brush the edge of the tart with the egg.
Bake for about 25 to 30 minutes or until the pastry is golden brown.