In a large pot warm the oil over medium heat. Add the garlic and crushed red pepper flakes and sauté until fragrant, but not browned, about 30 seconds.
Add the Parmesan rind, white beans, stock and sea salt. Bring to a boil over high heat and lower to a simmer. Cook partially covered for 10 minutes.
Slowly drizzle beaten eggs into hot soup, while constantly stirring the soup with a fork.
Stir in spinach leaves and cook until wilted.
Discard Parmesan rind and serve soup with grated cheese, if desired.