Preheat oven to 425 degrees F (see note). Line a half sheet pan with parchment paper.
Trim the ends off the zucchini. Thinly slice each zucchini into 1/8 to 1/4-inch rounds.
Scatter zucchini rounds evenly over half sheet pan. It's ok if they overlap slightly, but try to make sure they aren't doubling up completely. Try to keep the surface area of all the rounds as exposed as possible.
Drizzle the zucchini with the olive oil and sprinkle with salt.
Sprinkle the panko bread crumbs and Parmesan cheese evenly over the zucchini.
Bake for 15 minutes until the zucchini rounds are tender and the topping is golden. If you want the topping more golden, set the oven to broil, and broil the zucchini for the last minute or so of cooking (watch closely). Serve immediately.
Notes
Oven Temp:if your oven bakes cool or doesn't brown the tops of things very well, increase the temperature to 450 degrees F. Parmesan: I prefer freshly shredded Parmesan cheese (I use the small holes on a box grater). However, I'm guessing this recipe is pretty adaptable to whatever kind of Parmesan cheese you have on hand.