Lightly grease a slow cooker. Cut roast into 3-4 chunks and add to slow cooker, along with enchilada sauce, bullion granules, garlic, and onion.

Cover and cook on low for 6-8 hours, or until meat is tender. Remove meat from slow cooker, leaving sauce, and shred with two forks. Season beef with salt and pepper, to taste. Set aside.

Preheat oven to 400 degrees. Lightly grease a 9x13 in baking dish. Spread 1/3 cup of the sauce from the slow cooker in the bottom of the dish.

Place 1 1/2 cups of sauce from the slow cooker into a medium saucepan. Whisk in cream. In a small bowl, whisk together flour and water. Whisk the flour mixture into the sauce. Bring to a simmer over medium heat. Season with salt and pepper, to taste. Simmer while you prepare the burritos.

Divide the shredded beef evenly between the tortillas. Roll up and place seam side down in the prepared baking dish.

Pour the sauce over the burritos. Sprinkle with the cheese. Bake, uncovered, for about 20 minutes, or until cheese is melted and sauce begins to bubble.

Sprinkle with cilantro before serving. Serve with sour cream, pico de gallo and guacamole, if desired.