In a large skillet, over medium heat, saute the vegetables in olive oil until golden.
In a saucepan, heat 4 cups of water, add the lentils, and cover most of pan. Cook for about 15 minutes, or until soft.
Add the lentils to the vegetables, with salt and pepper to taste. Mash together with large spoon until creamy. Cover with broth, and add salt and pepper.
Meanwhile, bring a large pot of salted water to a boil. Cook the pasta until al dente, drain it, retaining some of the cooking water. Add the pasta to the lentils. Mix well together. Serve immediately with a sprinkle of Parmigiano.