Melt the vegan butter or add the olive oil to a saucepan on medium heat.
Add the flour of choice, little by little, as you stir with a wooden spoon.
Start adding the milk. When it starts to brown, cook it for 1 minute more and add the unsweetened milk.
Stir constantly with a whisk until it gets creamy and a thick sauce starts to form.
Season. Add salt, nutritional yeast, nutmeg, and pepper. Continue stirring and use immediately.
Notes
This sauce gets sticky very quickly, so; you should make it just when everything is ready to assemble.Plant milk: any plant milk will work here. Suitable creamy replacements for almond milk are unsweetened oat milk and soy milk.