Jumbo Shell Pasta Stuffed with Baby White Cheddar and Chicken Macaroni

Preheat the oven to 400 degrees F. In a large saucepan, cook both macaroni noodles separately according to package directions to al dente. Immediately rinse with cold water to stop cooking process. Drain and set each aside. In a large, heavy saucepan, melt 1/4 cup butter over medium to high heat; add flour and whisk 1 minute. Gradually whisk in milk and half-and-half; continue to cook over medium to high heat, stirring constantly, until thickened and bubbly. Stir in salt, pepper, and 3 cups shredded cheese, until melted. Stir in small-shell macaroni, chopped sun-dried tomatoes, and shredded chicken. Spray a 13 x 9-inch baking dish with nonstick cooking spray. Fill each jumbo shell carefully with white cheddar macaroni and place each side by side in dish. Sprinkle with remaining 1 cup shredded cheese. Stir together 2 tablespoons melted butter and crushed cornflakes. Sprinkle evenly on tops of shells. Bake 15 to 20 minutes or until golden brown on top.