To make vegetarian: Instead of chicken, feel free to use 1 can of drained and rinsed chickpeas or white beans. Add directly to couscous once it is done cooking.
To make gluten free: You can try using white basmati rice in place of the couscous, but please know that liquids and cooking times will differ.
To make vegan: Instead of using cheese, try using 1/2 Siete queso, a vegan queso. You can also make a homemade cashew cheese sauce and blend in.