Boil the potatoes in a pot.
Loosen the kataifi pastry by gently combing through it with your fingers. Spread it out evenly on a baking tray and brush with a little olive oil to help it bake evenly. Press it down firmly with another baking tray of the same size, place the tray on top, and bake at 170°C (340°F) for 30 minutes.
Once the potatoes are cooked, remove them from the water and gently crush them. Add a bit of salt if needed.
Finely chop the rosemary and mix it into the potatoes.
Grate the feta cheese directly over the potatoes, then add the egg, heavy cream, and freshly ground pepper. Mix well to combine.
Spread this mixture over the baked kataifi base and press it down gently so it sticks.
In a blender, process a small amount of kataifi until finely ground. In a small bowl, combine the grated hard cheese with the ground kataifi. Mix well and sprinkle evenly over the pie.
Place the pie back in the oven under the grill on medium heat until it turns golden brown.
Once ready, drizzle with tomato & herb balsamic cream and serve.