In a medium saucepan, on medium-high heat, saute onions, celery and carrot in 2 tbsp olive oil until translucent about 4-5 minutes.
Add garlic and saute for 1 minute until fragrant.
Add lentils, oregano, basil, bay leaf and tomatoes. Stir and cook for about 3 minutes.
Add broth and bring to a boil. Reduce heat to medium low and simmer for about 40 minutes until the lentils are tender.
In the meanwhile, bring a large pot of water to a boil over high heat. Add a tbsp of salt to the water and allow the water to return to a boil. Add the spaghetti and cook according to the package directions. When the spaghetti is cooked, drain the spaghetti and return it to the pot and pour half the lentils over the spaghetti and toss.
Transfer to individual bowls and top each bowl with more lentils, grated Parmesan and parsley.