Preheat the oven to 425 degrees F (218 degrees C).
In a large bowl, drizzle the sliced zucchini and squash with olive oil. Season with Italian seasoning, garlic powder, sea salt and black pepper. Toss to coat.
Arrange the vegetables in a single layer on a large baking sheet (half sheet pan, about 12”x17”). (You can line it with parchment paper first, or simply spray with cooking spray.)
Roast zucchini and squash in the oven for 10-12 minutes, until tender.
Optional step: If you want the zucchini browned more, broil for 3-6 minutes.