How to Make It
Sprinkle eggplant with 1/2 teaspoon salt. Place half of eggplant on a baking sheet; broil 5 minutes on each side or until lightly browned. Repeat procedure with remaining eggplant.
Bring water to a boil in a large Dutch oven. Add spinach; cover and cook 2 minutes or until wilted. Drain well. Place spinach on several layers of paper towels; cover with additional paper towels. Let stand 5 minutes, pressing down occasionally. Coarsely chop spinach.
Heat a medium skillet coated with cooking spray over medium heat. Add onion, red pepper, and garlic; cook 4 minutes or until onion is tender, stirring occasionally. Stir in lemon juice; cook 30 seconds or until liquid evaporates. Combine onion mixture and chopped spinach in a bowl; stir in 1/2 teaspoon salt and black pepper.
Combine fontina and Parmesan in a small bowl. Working with 1 eggplant slice at a time, spread about 2 1/2 tablespoons spinach mixture evenly over each of 14 eggplant slices; sprinkle each with about 2 teaspoons cheese mixture. Cover with remaining eggplant slices, and gently press together.
Combine milk and egg whites in a medium bowl, stirring with a whisk. Working with 1 sandwich at a time, brush both sides of each sandwich with milk mixture, and dredge in polenta.
Heat 2 teaspoons oil in a large nonstick skillet over medium-high heat. Add half of sandwiches; cook 5 minutes on each side or until browned. Repeat procedure with 2 teaspoons oil and remaining sandwiches. Serve with lemon wedges.