Heat the oil in a large Dutch oven or heavy pot until shimmering.
Add the onion, carrot, celery and one teaspoon of salt. Stir regularly until vegetables are softened. Add garlic and crushed red pepper (if using). Stir until fragrant (about 1 minute).
Add the tomatoes, white wine, bread, and broth. Bring to a boil and simmer for about 20 minutes.
Add the beans, bay leaf, thyme, and oregano. If using parmesan rind and kale, add them now. (NOTE: Spinach, if using, will be added later.) Bring to a boil and simmer until kale is tender and bread is almost dissolved, about 10 minutes.
Add spinach (if using) and continue simmering until spinach wilts. Season with black pepper and remaining salt to taste.
Remove bay leaf and parmesan rind before serving. Garnish with a drizzle of olive oil and/or grated parmesan cheese if desired.