Place the pasta in a 10" or larger skillet. Add cold water to cover. Add salt generously. Bring to boil, then reduce heat. Continue cooking until pasta is al dente, about 8 minutes. Add additional cold water if necessary.
While pasta is cooking, dice the squash and onion. Cut the green beans (or snap peas) into 1/2-inch pieces.
Add olive oil to sauté pan over medium heat, then add vegetables. Add salt and pepper and toss. Cook for about 5 minutes.
When the pasta is nearly ready, drain any remaining water. Add the vegetables to the pasta in the large skillet, toss.