1. Preheat the oven to 150°C/300°F/gas 2.
2. Infuse the olive oil with thyme by gently heating it with most of the thyme sprigs. Don't let it come to the boil. Once warm, turn off the heat and allow to cool whilst you prepare the chips.
3. Thinly slice the potatoes. I like to use a mandolin for this. Try and get them all the same thickness so they cook evenly.
4. Remove the thyme sprigs from the infused oil and pour over the potato slices. Mix to coat well.
5. Mix together the salt and chilli before sprinkling over the potatoes.
6. Lay them in one layer on baking sheets and transfer to the oven.
7. Bake for 20-25 minutes, or until crisp. Keep an eye on them as some may colour quicker than others and will need removing.
8. Allow to cool before serving with your favourite dip and the remaining thyme sprigs.