Cut the spinach leaves into large pieces. Add to a colander and season with salt. Toss with your hands and gently knead. Set aside for 5 minutes. Then wrap the spinach in a cloth and hand squeeze out any excess liquid.
spinach and feta cheese filling
Combine diced garlic, chopped spring onion, parsley, mint, dill, nutmeg, and feta cheese in a bowl. Add the greek yogurt, eggs, grated cheese, spinach, and lemon zest. Season with salt and pepper to taste. Preheat the oven to 210 °C / 410 °F. In a bowl, stir to combine the melted butter and oil. Grease the 20 cm x 30 cm (8-inch x 12-inch) baking sheet with butter and oil mixture.
layer and bake
Grab the phyllo (filo) sheets and cut them into the same size as your baking dish. To assemble the spanakopita: Line the baking dish with one phyllo (filo) sheet. Brush with the butter and oil mixture. Add another sheet and brush with the butter mixture. Repeat the process until you have five layers of pastry. Now, evenly spread the spinach filling over the phyllo (filo) pastry. Top with another sheet, and brush with olive oil. Repeat the process until you have five layers of pastry on top. Brush the last layer with the butter mixture. Sprinkle with sesame seeds and cut them into eight rectangles. Place in the preheated oven on the middle rack. Bake for 25 - 30 minutes at 210 °C / 410 °F. When the spinach pie bakes, transfer to room temperature to cool, then serve.