Wash the zucchini and squash, quarter them lengthwise, then cut them into 1-inch thick pieces.
In a bowl, toss zucchini and squash with olive oil, Italian seasoning, garlic powder, salt, and pepper until coated.
Place the seasoned vegetables in a single layer on a large baking sheet covered with parchment paper.
Roast in the preheated oven for 13-18 minutes, or until tender and lightly browned.