Preheat oven to 350. Spray a 9" x 13" with cooking spray. Melt butter in a large skillet over medium heat. Add rotel and saute for 2 minutes. Stir in cream cheese and chicken, stirring until melted. Remove from heat. Spoon 3 Tablespoons of chicken mixture in shell and roll. Place seam down in pan. Repeat with the remaining shells. Sprinkle with cheese, and drizzle cream over the top. Cover with foil. Bake in preheated oven for 30 minutes. Take off foil. and cook 15 minutes longer until golden brown.