Lightly oil the slow cooker. Add beef, chile Colorado sauce, bouillon, onion, garlic, salt, and pepper. Cook on low for 6–8 hours until tender.
Remove beef and shred with forks. Leave sauce in cooker. Taste and adjust seasoning.
Preheat oven to 400°F (200°C). In a saucepan, combine 1½ cups chile sauce with cream. Whisk flour and water until smooth, then stir into sauce. Simmer on medium until thickened.
Grease a 9x13 dish and spread ⅓ cup chile sauce on the bottom. Fill tortillas with shredded beef, roll tightly, and place seam-side down.
Pour creamy sauce over burritos. Top with cheese. Bake uncovered for 20 minutes until bubbly.
Sprinkle with cilantro. Serve with guacamole, pico de gallo, or sour cream.