Creamy, cheesy, and a delicious way to get those greens in!
Pre-heat the oven to 400°F.
In a large saucepan, heat the butter over medium-high heat. Add onion and cook until it is translucent (about 5 minutes) and then add in the minced garlic.
Add arrowroot flour and stir for one minute until well combined.
Pour in cashew milk and mix well. Bring sauce to a boil. Once at a boil, lower heat and let simmer until thick enough to coat the back of a spoon. (Make sure the sauce is thick)
Add in 1/2 cup of parmesan cheese and whisk until cheese is well combined.
In a separate pan, cook the spinach until it's wilted. (Do this in batches if necessary). Add all wilted spinach to the sauce and cook a few minutes more. Taste and adjust seasoning as needed.
Pour the spinach mixture into a greased casserole dish and top with parmesan cheese. Bake for 20 minutes or until bubbly and the cheese on the top is a golden brown.