Heat oven to 350°F.
Place cubed eggplant on cooking sheet on top of paper towels. Salt generously. Let sit for about 30 minutes. Remove paper towels and replace with foil. Sprinkle eggplant with about 1 tablespoon of olive oil. Roast eggplant in oven on middle rack about 30-40 minutes, or until eggplant is soft. (If you are in a time crunch, this ingredient can be removed.)
When eggplant is halfway through roasting, cook lasagna noodles according to instructions on box. Let noodles sit in colander until cool enough to handle.
When eggplant is done roasting, heat 2 tablespoons olive oil in a large skillet over medium-high heat. Sautee leek and mushrooms until soft and leeks are transparent. Add spinach. Sautee until wilted. Add eggplant. Add crushed red pepper (more or less based on how spicy you want your lasagna). Add crushed tomatoes. Turn off heat and set aside.
Combine ricotta and spices. Crack eggs into ricotta and incorporate completely.
In a 2-quart casserole dish, place a small amount of tomato mix in the bottom of the pan. (This will ensure the first layer of noodles doesn’t stick to the bottom.) Top tomato mix with three lasagna noodles, lengthwise, using kitchen shears to ensure noodles fit in pan. There may be some overlapping. Top noodles with tomato mix, ⅓ of ricotta mix then ⅓ of cheese. Start over again layering with noodles. You should have three layers when complete. The top layer should be cheese.
Place in oven. Cook about 30 minutes. If you want a crispier top, broil for 2-3 minutes at the end.
Cool for about 10 minutes before serving. The cooler the lasagna is, the easier it will be to cut and serve.
* Oftentimes, lasagna noodles stick when boiling so it’s best to cook at least one additional noodle than you need (this recipe needs nine) in case a noodle is ripped and not able to be used during assembly.