Sauté onion and carrots in olive oil for 5-6 minutes.
Add garlic and rosemary; cook for 1-2 minutes until fragrant.
Stir in white beans and broth; season with salt and pepper.
Bring to a boil, then reduce to a simmer.
Use a spoon to mash about 1/4 of the beans against the side of the pot to thicken.
Simmer for 10 minutes.
Stir in fresh spinach until just wilted (about 1 minute).
Remove from heat; stir in lemon juice and half the Parmesan.
Garnish with remaining Parmesan and a drizzle of olive oil.
Notes
Use a potato masher for a creamier texture.Rinse canned beans well to control sodium levels.Add a Parmesan rind to the simmering broth for extra depth of flavor.If using kale instead of spinach, add it earlier in the simmer process.This soup thickens as it sits; add a splash of broth when reheating.Store in an airtight container for up to 4 days or freeze for up to 3 months.