Preheat oven to 350 degrees F. Coat a 3-quart rectangular baking dish with cooking spray; set aside.
In a Dutch oven cook linguine according to package directions, adding broccoli for the last 2 minutes of cooking; drain. Return linguine mixture to Dutch oven.
Meanwhile, for sauce, in a large skillet heat butter over medium heat until melted. Add sweet peppers and garlic; cook about 5 minutes or just until peppers are tender, stirring occasionally. Stir in flour, salt, and black pepper. Add broth and milk all at once. Cook and stir until thickened and bubbly. Stir in sour cream.
Add sauce, turkey, and cheese to linguine mixture; stir gently to combine. Transfer mixture to the prepared baking dish. Cover with foil. Bake for 25 minutes.
Sprinkle with Bread Crumb Topper. Bake, uncovered, for 10 to 15 minutes more or until heated through and topper is light brown. Let stand for 5 minutes before serving.
Bread Crumb Topper
In a small bowl toss together bread crumbs, parsley, lemon peel, and olive oil.