Place onion, carrots and celery in a food processor.  Pulse until chopped very fine.

In a large saucepan, add a small amount of olive oil.

Add the vegetables and cook over medium-high heat until softened, 4 to 5 minutes.

Add the flour and cook for another 2 minutes, stirring the whole time.

Gradually stir in the broth and water and bring to a boil. Continue to cook, stirring, until thickened, about 5-6 minutes. Remove from the heat.

While the vegetable broth mixture is cooking, boil your pasta according to package directions.

Add the milk, cheese and noodles and stir until the cheeses melt.  Ladle into bowls and serve warm.