Preheat the oven to 225°F (110°C). Line two baking sheets with parchment paper for easy cleanup.
Prep the apples.
Wash and dry them well. You can core them if you prefer perfect rounds, but it’s optional.
Slice thinly. Using a sharp knife or mandoline, slice the apples into 1/16–1/8 inch (1.5–3 mm) rounds.
Thinner slices get crispier.
Optional soak. For a brighter color, soak slices in a bowl of cold water with a splash of lemon juice for 3–5 minutes, then pat dry thoroughly.
Arrange on trays. Lay slices in a single layer without overlapping.
This helps them dry out evenly.
Season. Mix cinnamon with sugar (if using) and a small pinch of salt. Lightly sprinkle over the apples.
A little goes a long way.
Bake low and slow for 1 hour. Rotate the pans and flip the slices. Continue baking for another 45–75 minutes, depending on thickness and water content.
Check for doneness.
Chips should look dry and feel mostly firm. They’ll crisp even more as they cool. If still soft, keep baking in 10–15 minute increments.
Cool in the oven.
Turn off the heat, crack the door, and let chips sit for 20–30 minutes. This step boosts crunch.
Store once fully cool. Transfer to an airtight container to keep their crisp texture.