In a sauce pan, heat butter and mushrooms on medium heat. Sauté for a few minutes, stirring occasionally. Then add in flour and stir thoroughly. Slowly pour in 2 cups of non-dairy milk and whisk together. Add in a pinch of nutmeg, salt and pepper. Bring to a boil and then reduce heat and let simmer for a few minutes until thick. Take off heat and set aside once done.

Meanwhile, hard boil your eggs in a saucepan with water for 15 minutes. Once done, set eggs in cold water to cool. Once cooled, remove shells and chop eggs. Cook pasta according to package directions and drain once done. Set eggs and pasta aside for now.

Now preheat oven to 350F. Add your mushroom roux from earlier to a large bowl. Then add in mayo, dill, parsley and 1/3 cup non-dairy milk. Stir together and mix in tuna and cheese. Slowly fold in the cooked pasta and eggs.

Scoop mixture into a casserole dish. Bake for 30 minutes, then remove from oven and sprinkle French fried onions across the top. Bake for 5 more minutes then take out of oven to cool for a couple minutes.