You can do two baking sheets at once to get a slightly larger batch—definitely do this if you're making these for more than one kiddo! Just be sure to swap the positions of the pans halfway through baking to ensure that they bake evenly.
Preheat the oven to 200 degrees F. Line a rimmed baking sheet with parchment paper.
Wash, dry, and remove the stems from the berries.
Use a mandoline to make slices that are about 1/8-inch thick (on my mandoline, the notch is between the 1 and the 2). Spread out on the prepared baking sheet without overlapping and bake for 60 minutes. Carefully turn the slices over.
Bake for an additional 15-30 minute or until mostly firm (and not sticky) to the touch. Remove pan from the oven and let cool on the sheet. (They crisp a little further as they cool.) Serve immediately or store in an airtight container for up to 2 days and store at room temperature.
Use a mandoline to make thin, uniform slices.
Place on a parchment-lined baking sheet or use a baking sheet with raised ridges to prevent sticking.
Let cool completely before eating for the best texture.