In a large pot or dutch oven, over medium heat, heat the olive oil and butter until the butter has melted. Add the shallot and garlic and sauté until softened and fragrant.

Add the flour and stir to combine, cooking for about a minute to get rid of the raw flour taste. Then, add the spinach and cook until wilted, about 5 minutes.

Add the heavy cream, chicken broth, nutmeg, cayenne, salt and pepper, and cook until thickened, about 5 minutes. Add the parmesan and stir to combine. Taste for seasoning and adjust if necessary.

If the soup is not thick enough, you can dissolve a bit more flour into some broth or heavy cream and add that mixture to the pot. Continue cooking until the soup is as thick as you'd like.

Serve immediately.