Preheat oven to 350°. Cook pasta according to package directions. Drain and rinse in cold water; drain again., Meanwhile, in a large skillet, cook and crumble beef over medium-high heat until no longer pink, 6-8 minutes. Stir in chili powder, cream cheese and 1/2 cup taco sauce until blended. Stir in 1/4 cup shredded cheese., Spoon about 2 tablespoons filling into each shell. Place in an 11x7-in. baking dish coated with cooking spray. Top with remaining taco sauce., Bake, covered, until heated through, 20-25 minutes. Sprinkle with remaining cheese; bake, uncovered, until cheese is melted, about 5 minutes. Sprinkle with chips., Freeze option: Cool unbaked casserole; cover and freeze. To use, partially thaw in refrigerator overnight. Remove from refrigerator 30 minutes before baking. Preheat oven to 350°. Cover casserole with foil; bake as directed, increasing time as necessary to heat through and for a thermometer inserted in center to read 165°. Top with cheese and chips as directed.