On day you would like to eat the casserole, preheat oven to 425 degrees. Line a large baking sheet with parchment paper.
Trim ends of fresh green beans. Add to a large bowl. Drizzle with olive oil, salt and pepper. Toss to coat.
Place in a single layer on baking sheet. Roast until just lightly caramelized, 10 to 12 minutes. Toss halfway through for even cooking.
While beans are cooking, cook one batch of The Gluten-Free Homemaker's Cream Soup. I make mine using unsweetened almond milk and arrowroot. Make sure to add the mushrooms at the end. You'll want a "cream of mushroom" soup for this dish.
Once soup has thickened, slowly whisk in additional 1 cup of milk until soup has a slightly less thick consistency, but is not thin. You want it thick enough to sit atop the green beans.
Remove green beans from the oven and place on serving platter. Gently spoon soup over the top of the green beans. (You may not want to add the entire batch of soup, save some to make this the next day or enjoy the soup on its own.)
Top with French fried onions and serve immediately.
Recipe and Photos Copyright Johnna Wright Perry, In Johnna's Kitchen. Do not reprint without express written permission.