I must admit that this isn't an original recipe with me...I got it from someone else, and I know they'd feel really complimented to know how much I like it and hope you will too! This takes a little bit of patience, but the preparation work will seem like nothing once you taste this divine dish!
On a cookie sheet lined with foil, put onions, garlic, parsley and eggplant which have been tossed in olive oil. Bake at 400 degrees for 15 minutes, stirring half way through.
Reduce heat of oven to 350 and put the eggplant mixture into a greased casserole dish (a deep one is best). Sprinkle with salt and pepper and several spoonfuls of parmesan.
Continue layering and salting/peppering and putting cheese on each layer in this order: zucchini, mushrooms, bell pepper and tomatoes (ending with top layer of parmesan cheese).
Bake in oven for 45 minutes. I keep the dish covered for 30 minutes and then remove the cover for the last 15 minutes. You may want to add some panko bread crumbs during the last few minutes of baking...adds a little garnish and some delicious crunch.