Lasagna, Swiss Chard

Ingredients

• 2 pounds red Swiss Chard, stems removed up to 1" from the leaves
• 3 tablespoons unsalted butter
• 1 small onion, finely chopped
• 2 tablespoons all-purpose flour
• 2 cups milk
• 1 bay leaf
• Salt and freshly ground pepper
• 1 pound shiitake mushrooms, stems discarded, caps sliced 1/4" thick
• 2 medium shallots, minced
• 2 cups ricotta cheese (8 ounces)
• 2 cups of grated mozzarella cheese(8 ounces)
• 2 large garlic cloves, minced
• 1 large egg yolk
• 1/2 cup of grated Parmesan Cheese (about 2 ounces)