Preheat oven to 225 degrees F (110 degrees C). Line 2 large baking sheets with parchment paper or silicone baking mats.
Place zucchini slices in a single layer on paper towels, cover slices with more paper towels, and gently press to squeeze out as much liquid as possible. Arrange zucchini slices onto the prepared baking sheets, taking care not to overlap slices.
Brush zucchini slices with olive oil and sprinkle lightly with kosher salt.
Bake zucchini slices in the preheated oven until browned and crisp, about 2 hours.
Let cool before serving. Store in an airtight container up to 3 days.
