Cook the penne in a large pot of salted boiling water until it is tender, about 10 minutes (time may vary with gluten-free pasta - see package for times). About 5 minutes before the pasta is cooked, add the broccoli and carrots. About 2 minutes before the pasta is cooked, add the zucchini. Drain the cooked pasta and vegetables well and return to the pot.
While the pasta is cooking, combine the drained cashews, garlic, and broth in a blender or food processor. Process until smooth and well blended.
Peel and pit the avocado and add it to the food processor along with the scallions, lemon juice, salt, and pepper to taste. Process until smooth and creamy. For a thinner sauce, add some almond milk, if needed. For a thicker sauce, add additional avocado. Taste and adjust the seasonings, if needed.
Add the sauce to the pot containing the drained cooked pasta and vegetables. Add the tomatoes and chopped basil and toss gently to combine. Serve immediately, garnished with the whole basil leaves.
Recipe by Go Dairy Free at https://www.godairyfree.org/recipes/creamy-vegan-pasta-primavera