Spray the eggplant rounds with a little olive oil spray, then place on a baking sheet and roast in the oven for about 20-25 minutes.
1 large eggplant
While the eggplant is roasting, slice the polenta into rounds.
18 ounces prepared polenta
In a medium bowl combine the ricotta cheese, Parmesan cheese, and egg.
16 ounces ricotta cheese, ¼ cup Parmesan cheese, 1 egg
Place the mushrooms in a microwave-safe dish and heat about 5 minutes on high, stirring halfway through, to soften them slightly.
16 ounces sliced mushrooms
Once the eggplant is done, remove from the oven and turn it down to 350 degrees F (175 degrees C).
Spread a little of the marinara sauce on the bottom of a 9x13 casserole pan. Place half of the polenta rounds on top of the sauce.
24 ounces marinara sauce
Spread half of the ricotta mixture on top of the polenta.
Place half of the eggplant rounds on top of the ricotta mixture. Distribute half of the mushrooms on top of the eggplant.
Sprinkle half of the mozzarella cheese on top of the mushrooms, then spread half of the remaining marinara on top of the cheese.
12 ounces shredded mozzarella cheese
Then repeat layers: place the remaining polenta rounds, ricotta mixture, eggplant, mushrooms, and sauce.
Cover the dish with aluminum foil and bake for 30 minutes, then remove the foil, sprinkle the rest of the mozzarella, and bake for about 15 additional minutes.
Video
Notes
Keep an eye on the eggplant while it's roasting. Some thinner slices might start to burn before the thicker slices are cooked.
If your family doesn't like mushrooms, simply omit them.
For extra flavor, stir some Italian seasoning or spaghetti seasoning into the sauce (start with 1 teaspoon and add more as needed). If you don't have these seasoning mixes handy, check out my homemade Italian seasoning and spaghetti seasoning recipes!