Use a saucepan large enough to hold the lentils and pasta with enough water to cook them. Add 2 tbsp (30 ml) olive oil, bacon, onion, garlic, celery, and parsley. Cook over medium heat, stirring often, until the vegetables are deeply colored, about 15 minutes. Add tomato, stir to coat, and cook a few minutes until the fat separates from the tomato.
Add the lentils, turning them a few times to coat. Add enough water to cover by 1 inch (2.5 cm). Simmer gently until the lentils are tender, about 25 to 30 minutes, adding water as needed to keep the level.
Add salt and several grindings of pepper, add the pasta, and raise heat to a brisk boil. Add more water if needed. Cook until the pasta is tender but still firm to the bite, keeping the soup on the dense side.
Taste and adjust salt and pepper. Stir in the cheese and about 1 tbsp olive oil, mix well, then take off heat and serve at once.