Place chicken thighs in an oil sprayed slow cooker. Cover with salsa and add a dash of chicken broth or water so they are covered in liquid but not submerged. Cook 4 hours on high [or 6-8 on low]. Remove from cooker and shred. At this point you can store chicken in refrigerator for up to 2 days or freeze.
To make casserole. Combine sour cream, soup & Rotel in large sauce pan and simmer over medium low heat, stirring occasionally. Once combined, spoon about 1/3 of sauce into a sprayed casserole dish and spread out into an even layer.
Lay out tortillas on clean counter top or paper towels. Divide chicken among tortillas and sprinkle with 1-2 T cheese. Top with 1-2 T sour cream, and 1-2 T creamed corn.
Roll up and place seam side down in dish, squeezing to fit. Cover with remaining sauce and sprinkle with cheese. Bake 325 until bubbly, 45-60 min. If casserole is cold it will take at least an hour. If cheese is getting too brown, cover casserole loosely with foil. Serves 6-8.