Pour the enchilada sauce and apple butter in a Crock-Pot. Place the beef roast in it, followed by sliced onions, garlic, salt and red pepper. Cover and turn the Crock-Pot on high for 4 to 5 hours, until the beef is falling apart.
Using two forks, shred the beef roast into the sauce, and leave on warm until ready to serve.
For the Beef Nachos: Preheat the oven to 350 degrees F. Arrange the tortilla chips on a large rimmed baking sheet. Sprinkle half the cheese over the top and bake for 3 to 5 minutes to melt the cheese.
Scoop the chili con carne over the chips, and sprinkle the remaining cheese over the hot beef. Top with any additional toppings and serve immediately.