Preheat the oven to 130°C
To ensure crispness, slice the apples as thinly as possible all around the apple. I like to use a potato peeler for this. Slice one side and then turn the apple 1⁄4 of the way and slice then keep going. The slices don’t have to be uniform. When did you last buy a bag of crisps to find they were all a uniform size?
2 tablespoons sugar
1 tablespoon ground cinnamon
4 Granny Smith or other tart apples, thinly sliced
Line 2 baking sheets with parchment paper. Place the sugar and cinnamon in a large bowl and mix well. Add the apple slices and toss until most of both sides of the apples are well coated. Place the apples, in a single layer, on to the baking sheets, transfer to the oven and bake until lightly browned and just crisp, about 2 hours. Set aside to cool and then transfer to a jar or plastic bag.
Preheat the oven to 200°C
For a really simple treat, slice it really thinly, brush with oil and roast in the hot oven until you get sweet beetroot crisps,
NB: Note the difference in the oven temperatures here Apples go in a cool oven and the beetroot needs a hot oven, so no chance of baking them at the same time.