Cook rice according to package instructions. Set rice aside to cool while you’re prepping the rest of the recipe.
Preheat the oven to 400 degrees F.
In a large mixing bowl, whisk together the almond milk, eggs, mayonnaise (or butter), sea salt, stone ground mustard, and 2 cups of the mozzarella cheese to a mixing bowl (you’ll use the remaining 1 cup of cheese for the topping). Whisk this mixture together until it is well-combined. Add the drained tuna and rice and mix well to combine.
Transfer to a mixing bowl to a casserole dish (I use an 9” x 9” square casserole dish).
Top the casserole with the remaining cheese (add more if desired!) and place on the center rack of the preheated oven. Bake for 20-30 minutes, or until the cheese is melted and begins turning golden-brown and the center of the casserole reaches 160 degrees Fahrenheit. To check the internal temperature of the casserole, insert a meat thermometer into the center and wait until the numbers stop moving. Allow casserole to cool 5 to 10 minutes before serving.
