Preheat the oven to 425 degrees Fahrenheit. Line a large baking sheet with parchment paper or aluminum foil.
Quarter the zucchini and squash, then slice into 1-inch pieces. Arrange in a single layer on the prepared baking sheet. Drizzle the olive oil over the zucchini and toss to evenly coat.
Sprinkle evenly with Italian seasoning, salt, and pepper (more or less to your taste).
Roast squash for 12-15 minutes, tossing with a spatula halfway through the cook time to ensure even browning.
Garnish with grated Parmesan, if desired, and serve immediately.
Notes
Storing Leftovers: Leftover roasted zucchini can be stored in an airtight container in the fridge for 3 days. Because of the high water content, freezing is not recommended. Reheating: To reheat your zucchini, add it to a skillet over medium-low heat and saute until warmed through. You can also reheat it in the microwave or air fryer.