Line a shallow rimmed baking sheet with parchment paper and preheat the oven to 400.
Slice the ends off the zucchini and slice into 1/2" thick slices.
Lay in a single layer on the parchment paper with at least 1/2" space between each slice. If you need to use a second baking sheet, do that so everything has enough space.
Drizzle over the oil and use your hands or a pastry brush to spread it around. The zucchini doesn't need a solid coating of oil on each slice.
Sprinkle over the salt and pepper. You can toss the zucchini if needed to evenly spread the salt and pepper but it's optional.
Bake on the center oven rack 12-15 minutes. You can turn the slices over halfway through cooking if you'd like to but it's not required. Usually your zucchini slices will get golden on the bottoms much faster than the tops will.