Sauté Aromatics: Heat the extra virgin olive oil in a large Dutch oven or heavy pot over medium heat. Add the diced onion and sauté for 5 to 6 minutes until translucent and soft.
Season: Add the minced garlic, dried Italian seasoning, and red pepper flakes. Stir continuously for 1 minute until highly fragrant, being careful not to burn the garlic.
Combine: Pour in the rinsed cannellini beans and vegetable broth. Stir thoroughly, scraping up any browned bits from the bottom of the pot. Drop in the Parmesan rind if using.
Simmer: Bring the stew to a boil, then reduce the heat to medium-low. Simmer uncovered for 15 to 20 minutes, stirring occasionally.
Thicken Naturally: Use the back of a sturdy wooden spoon or a potato masher to smash approximately one-third of the beans against the side of the pot. Stir the mashed beans back into the broth to create a naturally thick and creamy texture.
Melt Cheese: Remove the pot from the heat source and discard the Parmesan rind. Slowly stir in the grated Parmesan cheese until it is entirely melted and incorporated into the velvety broth.
Wilt Greens: Return the pot to low heat and fold in the fresh spinach or kale. Cook for 2 to 3 minutes until completely wilted.
Finish & Serve: Remove from the heat completely. Stir in the fresh lemon juice, then season with sea salt and freshly cracked black pepper to taste. Serve warm with crusty bread.