Heat oven to 350°F. Cook pasta shells as directed on package. Drain; rinse with cold water to cool.
Meanwhile, in 12-inch skillet, cook sausage, garlic and oregano over medium heat 8 to 10 minutes, stirring occasionally, until sausage is no longer pink; drain. Stir in pasta sauce and tomatoes. Spread 1 cup of the meat sauce in ungreased 13x9-inch (3-quart) glass baking dish.
In medium bowl, beat egg. Stir in ricotta cheese and 2 cups of the Italian cheese blend. Spoon cheese mixture into gallon-size food-storage plastic bag; seal bag. Cut 1-inch hole in one bottom corner of bag. Squeeze bag to pipe about 1/4 cup cheese mixture into each pasta shell. Arrange stuffed shells over meat sauce in dish. Pour remaining meat sauce evenly over shells.
Cover dish with foil. Bake 35 to 40 minutes or until hot and bubbly. Top with remaining 1 cup Italian cheese blend. Bake uncovered 5 to 10 minutes longer or until cheese is melted. Sprinkle basil over top before serving.