Cut off the ends of the eggplant, then slice lengthwise about ⅛-inch (3-mm) thick.
Sprinkle the eggplant slices with sea salt on both sides and let sit for 10 minutes to draw out moisture. Pat dry with paper towels to remove 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, or until grill marks are visible. Remove from the pan and set aside.
In a medium saucepan, heat a drizzle of olive oil over medium-low heat, then add the garlic and red pepper flakes. Sauté for about 3 minutes, until the garlic is fragrant but not browned. Add the crushed tomatoes and 1 teaspoon of salt, stirring well to incorporate the garlic and red pepper. Simmer for 10 minutes, reducing the heat if the sauce begins to bubble too much. Add the basil and stir to combine. Remove from the heat and set aside.
In a medium bowl, beat the egg, then add the ricotta, 1½ cups (150 g) of mozzarella, ¾ cup (80 g) of Parmesan, and the Italian seasoning. Mix well to combine.
Assemble the lasagna. In a 9x13-inch (23x33-cm) baking dish, add enough sauce to cover the bottom of the dish and spread in an even layer. Add a layer of eggplant slices, covering the bottom of the dish completely. It’s okay if the eggplant slices overlap slightly. Add a layer of the ricotta mixture and spread in a thin, even layer. Repeat with the remaining ingredients, finishing with a layer of sauce. Sprinkle the remaining mozzarella and Parmesan on top.
Bake for 45 minutes, until cheese is fully melted.
Turn the broiler on high and broil for 5 minutes, or until the cheese on top is browned and bubbly.
Remove the lasagna from the oven and let rest for 15-20 minutes before serving to give the lasagna time to set.