1) Heat oven to 375. In medium bowl, mix pasta sauce, water, and garlic powder. In ungreased 13x9-inch baking dish, spread about one-third (1 cup) of the pasta sauce mixture.
2) If there are not 14 chicken tenders in your package, cut the larger tenders in half until you get 14 total (because there are 14 manicotti shells to stuff). Sprinkle the italian seasonings over the raw shicken tenders. Stuff the chicken tenders into the uncooked manicotti shells. Place shells on pasta sauce mixture in baking dish. Pour remaining pasta sauce mixture evenly over shells, covering completely.
3) Cover with foil. Bake 45 to 50 minutes. Sprinkle with cheese (and extra italian seasonings if desired). Bake uncovered 2 to 4 minutes longer until cheese is melted.
Optional: Top with tomato and pesto before serving.