Preheat oven to 425°F. Wash and trim squash, then cut into ¼-inch rounds and pat dry.
In a bowl, whisk olive oil, garlic, salt, pepper, and Italian seasoning. Toss squash until well-coated.
Arrange squash on a baking sheet, sprinkle half the Parmesan, and roast for 12 minutes. Flip, add remaining Parmesan, and roast for another 8-12 minutes.
Remove from oven, sprinkle with parsley and red pepper flakes if using. Serve hot.
Notes
For extra crispiness, ensure squash is well-dried before coating.