Preheat the oven to 400F.
Add the oil to a large skillet over medium-high heat. Add the ground chicken and sauté until almost browned, about 5 -7 minutes. Then add the tomato paste, chicken stock, and taco seasoning. Mix and continue to sauté for another 2 - 3 minutes, then set aside.
Slice the thawed Puff Pastry into 6 portions for each sheet. This will make 12 taco shells.
Take out two baking sheets and line with parchment paper. Divide the cheese into twelve portions and place directly on the parchment paper. Top each evenly with the cooked ground chicken, then top each pile with a pastry sheet. Crimp on the edges to seal.
Mix the egg and water, brush each pastry sheet with the egg wash.
Pop into the oven and bake for 15 minutes. Remove and flip each pastry sheet “taco” with a spatula. Place on a serving plate or platter.
Add whichever topping suggestions you enjoy most an enjoy immediately.