Thinly slice potatoes, plum tomatoes, yellow squash, and zucchini. Set aside. To give the tomatoes a little extra kick, I placed the thin slices on a paper towel to absorb some liquid and sprinkled 1 tsp or the multipurpose seasoning.
Saute your chopped onions and minced garlic in 1 tbsp of butter until onions are soft (about 5 minutes).
Spray a pie pan with non-stick spray and layer onions on the bottom of the pan. If you do not have a pie pan, an 8×8 pan will also work.
Create a spiral layer (or rows if you are using a square dish) of potato, zucchini, squash, potato, tomato, potato, zucchini, squash, potato, tomato, potato, etc…
Drizzle with the 2 tbsp of olive oil and sprinkle with the remaining 1 tsp of seasoning and salt. Cover with aluminum foil. Bake at 400 degrees, covered for 30 minutes.
Remove from oven and sprinkle with your Italian cheese. Bake uncovered for an additional 15-20 minutes.