Cook the spinach in the microwave for 60 seconds, then when able to handle, squeeze the spinach in a clean kitchen towel to remove the moisture. Finely chop the spinach.
Combine the spinach with the ricotta, basil, parsley, 3/4 cups mozzarella, 1/4 cup pecorino, and a half teaspoon of pepper. Mix well and taste test. Adjust salt levels to desired taste and then add 1 beaten egg and mix to combine.
Preheat the oven to 400°F and set the rack to the middle level.
Rinse the zucchini to remove the excess salt and dry off thoroughly with paper towels.
On a large clean surface layer 3-5 pieces of zucchini lengthwise overlapping each other. Place 2-3 tablespoons of the ricotta mixture in the middle of the zucchini layers. Roll up the zucchini and leave the seam side down. Work in batches until all of the zucchini slices are used up.
Layer a half inch of marinara sauce into the bottom of a large baking dish. Place all of the zucchini rollatini, seam side down, into the baking dish. Spoon some more of the sauce onto each rollatini and sprinkle with the remaining mozzarella and Pecorino Romano cheese.
Bake for 20-30 minutes or until bubbly and golden on top. The rollatini can be broiled for the last 1-2 minutes but watch carefully. Let rest for 15 minutes before serving so that the rollatini can settle. Any extra sauce can be served on the side. Enjoy!