Preheat the oven to 375 degrees (or the temperature listed on the package of burritos). Grease a 9x13 baking dish. Place the frozen burritos seam-side down in the baking dish. Evenly spread the taco sauce and salsa over the burritos. Place the baking dish in the oven and bake at 375 degrees F for 45 minutes or until the internal temperature of the burritos is 165 degrees F (use an instant read thermometer). Top the burritos with the shredded cheese and return to the oven to melt the cheese (about 5 more minutes). Serve the burrito casserole hot.