2) Prepare the bechamel sauce by melting the butter over a medium heat in a saucepan. Add the flour and whisk until smooth, about 2 minutes. Gradually add the milk while continuing to whisk, until the sauce is smooth. Simmer for about 10 minutes until the sauce is thick enough to coat the back of a spoon. Stir in the salt, pepper and nutmeg. Set aside.
3) For the spinach filling, heat 1 tbsp of oil in a large saute pan over a medium heat. Add half the spinach, stirring until wilted and tender, about 3 minutes. Remove the spinach, place in a colander and squeeze out any excess liquid, then roughly chop. Repeat the process with the remaining spinach.
4) Heat the remaining olive oil and 15g of butter in the saucepan and add the garlic. Saute until fragrant, about 1 to 2 minutes, then add the spring onions. Saute for another 2 to 3 minutes until the onions are soft, then add the spinach along with the parsley, nutmeg, salt and pepper.
5) Remove from the heat and allow to cool. Stir the feta cheese and beaten egg into the cooled spinach mixture.
6) Coat the bottom of a 33cm by 23cm lasagne dish with a thin layer of the bechamel sauce. Arrange four pasta sheets lengthwise on the sauce, slightly overlapping each other. Pour 1/3 of the bechamel sauce over the pasta. Then add 1/3 of the spinach mixture, spreading it out evenly. Top the spinach mixture with 20g Parmesan cheese. Repeat with two more layers of pasta, sauce, spinach mixture and Parmesan.
7) For the topping, unroll the filo pastry on a flat surface; keep it covered with a damp towel so it doesn't dry out. Place a sheet of filo on top of the lasagne. Brush with melted butter and sprinkle some breadcrumbs evenly over the top. Top with another filo sheet, brush with more butter and sprinkle with more breadcrumbs. Repeat with the two remaining layers of pastry.
8) Make sure the edges are nicely sealed with butter so they don't curl up during the baking process. Top the final layer with a mixture of the remaining melted butter, breadcrumbs and Parmesan.
9) Bake in the preheated oven for 25 to 30 minutes, being careful not to overcook the filo. Remove from the oven and allow to cool slightly. Cut into squares and serve.