In a large sauté pan, heat the olive oil. When the oil is hot, add the onion and garlic and sauté until translucent. Add the zucchini, parsley, and the crumbled bouillon cube.
Cook, uncovered, over low heat for about 20 minutes, until the zucchini are fully cooked and soft. If the zucchini seem dry, add a small amount of water to continue cooking until soft. It should look like a mush of zucchini. Taste for salt. If needed add salt to taste. Add freshly ground black pepper to taste.
When the zucchini are cooked, place the mixture in a blender and puree until you have a smooth sauce.
Bring the water for the pasta to a boil, add salt to taste, and cook the pasta until al dente.
While the pasta is cooking, place the sauce in a large sauté pan, and add the grated cheese. Mix well.
When the pasta is ready, drain, and add to the sauce, raising the heat and stirring until the pasta is well coated. Sprinkle with more cheese and serve at once.