Beat 2 eggs in a bowl. Pour bread crumbs onto a plate. Dip sliced eggplant into beaten eggs; coat with bread crumbs.
Heat oil in a skillet over low heat. Increase heat to medium; place eggplant in skillet. Cook until browned, about 4 minutes per side.
Combine remaining egg, ricotta cheese, spinach, garlic powder, and Italian seasoning in a large bowl.
Place eggplant slices in a single layer in a 9x13-inch casserole dish. Spoon 2 tablespoons of the ricotta mixture onto each eggplant slice; top each slice with 2 tablespoons pasta sauce. Sprinkle shredded mozzarella over each eggplant slice; cover with aluminum foil.
Bake in the preheated oven until cheese is melted and bubbly, about 30 minutes.