In a large fry pan with lid, add the olive oil and onions; cook over medium-low heat for 5 minutes or until onions begin to turn soft and slightly translucent.

Add garlic and continue cooking over medium-low heat for another 2-3 minutes, stirring occasionally.

Add tomatoes (undrained) and red pepper flakes. Stir and heat over medium heat until simmering. Let simmer for 5 minutes.

Increase heat to medium-high and add the mussels; stir and cover pan. Cook for 5-6 minutes, gently shaking pan every 1-2 minutes. Do not remove lid during this stage as it will prevent the mussels from steaming. (Note: This would be a good time to begin cooking the angel hair pasta in boiling water.)

After 5-6 minutes, open lid and remove those mussels which have already opened. Place lid back on pan and continue cooking for 2-3 more minutes. Remove mussels which have opened; discard any that have not opened yet.

Place mussels over angel hair pasta and top with several generous ladles of the tomato-garlic broth. Garnish with chopped basil and shaved Parmesan cheese. Serve with a large piece of French or Italian bread.