Step 1

Heat oven to 350°F. Cook pasta as directed on package without added salt until tender. Rinse with cool water; drain. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. Drizzle 2 tablespoons of the Buffalo sauce over bottom of baking dish; spread evenly.

Step 2

Meanwhile, in medium bowl, mix ricotta cheese and egg until well blended. Add chicken, remaining Buffalo sauce and 1/2 cup mozzarella cheese.

Step 3

Spoon about 3 tablespoons chicken mixture into each cooked pasta shell. Place in baking dish, filling side up. Cover tightly with foil.

Step 4

Bake 30 to 35 minutes or until filling is hot and meat thermometer inserted in center of chicken mixture reads 160°F. Sprinkle with 1 cup mozzarella cheese. Bake uncovered 5 minutes longer or until cheese is melted.

Step 5

Sprinkle with tomatoes, green onions and blue cheese. Serve immediately.