Cut off the ends of the eggplant, then slice lengthwise about ⅛-inch (3-mm) thick.
Season them with salt to taste on both sides and let sit for 10 to 15 minutes to draw out moisture. Pat dry with paper towels to remove any excess liquid.
Lightly grease a griddle pan with olive oil and heat over medium heat. Grill the eggplant slices for 2-3 minutes on each side. Remove from the pan and set aside.
In a big bowl mix the ricotta cheese with the baby spinach, red pepper flakes, salt and pepper to taste, minced garlic cloves and Italian seasoning.
To assemble the lasagna add some tomato sauce in a casserole baking dish and lay a single layer of cooked eggplants.
Spread a layer of the mixed ricotta cheese, tomato sauce and sprinkle some of the grated vegan mozzarella cheese.
Repeat the same process: eggplant, ricotta cheese, vegan mozzarella one more time and finally finish with eggplant, tomato sauce and grated mozzarella cheese.
Sprinkle dried oregano on top and cook the lasagna in an already heated oven at 350 F or 180 C degrees for about 30-35 minutes.
Garnish the plate with thinly sliced basil on top.