3 large shallots, peeled and cut into 1/2-inch-thick slices
2 pounds baby pattypan squash
3 tablespoons olive oil, divided
3/4 teaspoon kosher salt, divided
3/4 teaspoon black pepper, divided
2 pints cherry tomatoes
1/4 cup chopped fresh basil
2 tablespoons chopped fresh chives
2 teaspoons minced fresh garlic
3 1/2 cups fat-free, lower-sodium chicken broth
5 tablespoons all-purpose flour
1/4 cup heavy whipping cream
1 1/2 tablespoons Dijon mustard
1 large egg, lightly beaten
Cooking spray
9 cooked lasagna noodles
1 1/2 ounces grated fresh Parmigiano-Reggiano cheese (about 1/3 cup)
3 ounces fontina cheese, shredded (about 3/4 cup, packed)
2 tablespoons torn fresh basil