1. Heat oven to 400 degrees . Coat a 13 x 9 x 2-inch baking dish with nonstick cooking spray.
2. In a large nonstick skillet, heat olive oil over medium-high heat. Add garlic, Swiss chard, mushrooms, 1/4 tsp of the salt and the black pepper. Cook 7 minutes, stirring occasionally. Spoon off any excess liquid.
3. Meanwhile, in a medium saucepan, melt butter over medium heat; stir in flour and cook 1 minute. Gradually whisk in milk. Bring to a simmer; cook, stirring frequently, 3 minutes or until thickened. Add remaining 1/4 tsp salt, the nutmeg and cayenne.
4. Cook lasagna noodles following package directions, about 10 minutes. Drain. Combine ricotta, Fontina and egg.
5. Spread 1/4 cup of white sauce in baking dish. Layer as follows: 3 noodles, ricotta mixture, 3 noodles, 1 cup of the sauce, chard mixture, 1/2 cup of the mozzarella, 3 noodles, remaining 11/2 cups mozzarella and 3 noodles. Spread remaining 3/4 cup sauce over noodles and sprinkle Grana Padano over top.
6. Cover and bake at 400 degrees for 30 minutes. Uncover and bake an additional 20 minutes. Cool 20 minutes before serving.