To make this delicious Slow Cooker Green Chile Chicken and Rice Casserole gluten-free you just need to make adjustments. Start by checking that your enchilada sauce is labeled gluten-free as some brands may contain gluten. For the chicken seasoning. Choose certified gluten-free spices or create your own blend from scratch. Don't worry about the chicken itself fresh and unprocessed chicken is naturally free of gluten. The main ingredient, rice is gluten-free too. It provides a safe and comforting foundation, for this dish.