Preheat oven to 400F.
Add the potatoes and leeks to a large sheet pan lined with parchment paper. Toss with the olive oil and a generous seasoning of salt and pepper (about 1 tsp salt and 1/2 tsp pepper).
Roast for 40-45 minutes until lighly golden brown and tender. If you are planning to use bacon as a garnish, go ahead and bake it at the same time! Simply add the slices to a sheet pan lined with parchment and roast for 30 minutes, or until cooked through and crispy nicely.
Add the arugula, if using, and toss to combine. Roast for another 5 minutes until arugula is wilted.
Add entire sheet pan contents to a large soup pot (easy hack: gather the 3 corners of the parchment paper and slide the contents into the pot from the empty corner). Stir in the wine (if using) and 1 cup of chicken broth and bring to a simmer over low heat, stirring until the alcohol smell dissapears (a minute or two).
Add remaining chicken broth (If not using wine, you can add all the broth at once) and puree soup using an immersion blender until desired consistency. You can also transfer it to a blender and puree in batches if preferred.
Stir in the cashew cream, nutritional yeast, and salt and pepper to taste (usually another tsp of salt and 1/2 tsp of pepper), bring to a gentle simmer. Check seasoning and adjust as needed (add more nutritional yeast or cheese for a cheesier flavour, add more chicken broth for a thinner consistency, add more salt and pepper for flavour).
Serve hot with optional garnishes of choice. Today I used crisped bacon, parsley, and aged cheddar cheese. This soup goes well with some crusty bread and a simple green salad.