• Using a mandolin or a sharp knife, slice the zucchini into thin slices. Place the zucchini slices on a baking rack and sprinkle with salt from both sides. Allow to sit for 15-20 minutes to release its moisture. Then remove the salt and the moisture using a paper towel.

Make the sauce:

• In a pan, heat 2-3 tablespoons of olive oil, add chopped onion and sauté until golden, about 6-7 minutes, add garlic and cook for 2 minutes. Add tomato sauce, thyme, oregano, salt, black pepper, mix and cook for 5 minutes. Set aside.

Make the filling:

• In a large bowl mix ricotta cheese, feta cheese, 2 tablespoons of parmesan, 2oz (60 grams) of shredded mozzarella, lemon zest and black pepper. Note: at this stage, you can add any spices that you like. Taste to check the seasoning, if needed add more spices.
• In a pan cook spinach for 4-5 minutes, until wilted. Transfer the spinach to a cutting board and roughly chop. Add chopped spinach to the cheese mixture and mix until combined.
• Transfer the filling into a pastry bag.
• Preheat oven to 375F (190C).

Assembly:

• Spread a quarter of the sauce on the bottom of a 9-inch (24cm) diameter pan. Take zucchini slices and roll them into tubes. Arrange them tightly on top of the sauce. Fill each tube with the cheese mixture.
• Sprinkle some about 3oz (120g) of shredded mozzarella cheese on top, sprinkle 2 tablespoons grated parmesan.
• Bake until melted, about 25-30 minutes or until melted and golden.