Heat olive oil over medium heat in a medium-sized skillet, about 1 minute. Add scallions and garlic; saute in the hot oil until tender, 2 to 3 minutes. Add zucchini and squash; season with Italian seasoning, salt, and pepper. Saute until squash is tender, 8 to 12 minutes.
Divide mixture evenly among plates. Garnish with basil.