Preheat oven to 400 degrees.
Bring a large pot of water to a boil. Add the penne pasta and cook for 8 minutes. Add the broccoli and boil for 3 minutes more. Drain well. Return the pasta and broccoli to the now empty pot, add the sliced chicken and set aside.
In a small bowl with a spout, whisk together the evaporated milk, milk, flour, half the Parmesan cheese, salt and pepper. Set aside.
Pour the olive oil in a medium saucepan and heat on medium until shimmering. Add the chopped shallots and sauté for 3 minutes. Add the garlic and cook just until fragrant, about 30 seconds. Stir in the lemon rind and lemon juice; cook for another 30 seconds. Add the milk mixture, reduce the heat to medium-low and cook, stirring constantly, until the sauce is thickened, about 3-4 minutes.
Pour the white sauce over the pasta, chicken and broccoli and gently fold together to combine.
Lightly coat a 2.5 to 3-quart glass or ceramic baking dish with vegetable spray. Spoon the pasta mixture into the dish. Sprinkle the remaining Parmesan cheese on top, then the mozzarella and panko bread crumbs. Bake at 400 degrees for 10 minutes or until lightly browned.