1Heat oven to 350°. Spray rectangular baking dish, 13x9x2 inches, with cooking spray. Cook and drain pasta shells as directed on package.
2While shells are cooking, melt margarine in 12-inch nonstick skillet over medium-high heat. Cook onion and bell pepper in margarine 2 to 3 minutes, stirring occasionally, until crisp-tender. Stir in asparagus. Cover and cook 3 to 5 minutes, stirring occasionally, until asparagus is crisp-tender; remove from heat. Stir in shrimp, crabmeat, 1/2 cup of the pasta sauce and half of the basil.
3Spread about 1/4 cup of the remaining sauce over bottom of baking dish. Fill each cooked pasta shell with about 2 tablespoons of the seafood mixture. Arrange in dish. Spoon remaining sauce over shells. Sprinkle each filled shell with Parmesan cheese and remaining basil. Bake uncovered 25 to 30 minutes or until bubbly.