Slowly sauté leeks, shallots, and garlic in olive oil until soft
Add half a can of beans and cook for 5 minutes
Add chicken stock and reduce by half
Remove from heat and blend smooth with a hand emulsifier
Add butter, Parmesan, two pinches of salt, and remaining beans
Return to heat for 10 minutes
Boil fiorelli in heavily salted water until just before al dente
Add pasta to sauce and continue cooking for 3 minutes
Loosen with a ladle of pasta water if needed
Serve with more grated Parmesan
