Preheat your oven to 350 degrees.
Bring a pot of salted water to a boil.
Cook the pasta according to the package instructions for al dente.
Once the pasta is cooked, drain and rinse with cold water, and then set it aside.
While the pasta is cooking, saute the onion in avocado oil spray in a pan over medium heat for 4-5 minutes until it becomes soft and translucent.
Add the peas and continue to cook for another 1-2 minutes until they thaw.
Add the flour and stir for about 2 minutes until it starts to smell like it is getting toasted.
Whisk in the almond milk and vegetable broth and continue to whisk for about 5 minutes until the mixture starts to thicken.
In a large bowl, stir the pasta, tuna, onion/pea/cream sauce mixture, and cheese until combined.
Transfer to a 9 x 13 baking dish.
Top with panko bread crumbs and bake for about 15-20 minutes until the cheese has melted and the topping has started to brown.
Allow the casserole to cool for 5 minutes before serving.
Garnish with fresh parsley, if desired.