Heat a dry frying pan, then add the walnuts and lightly toast for a few minutes until they begin to darken and smell fragrant, stirring often so they don’t burn.
Add the toasted walnuts, parsley, garlic, lemon juice and salt and pepper to a small food processor and whiz until it forms fine crumbs.
Keep the motor running and slowly pour the olive oil in through the feed tube, whizzing until it’s all combined. Store in an airtight container in the fridge for up to 1 week.
For the maple glazed walnuts
Heat a dry frying pan over a medium heat. Add the walnuts and lightly toast, shaking the pan often, for a few minutes until golden and fragrant.
Add the maple syrup, brown sugar, rosemary, paprika and sea salt and heat, stirring, for a minute or two until the sugar dissolves. Spread the nuts onto a plate to cool.
For the salad
Core and quarter the apple then slice it thinly. Add the lemon juice to a bowl of cold water and put the apple slices into it for a few minutes to prevent browning.
Gently toss the salad leaves together with the drained apple in a large serving bowl. Just before serving, add a drizzle of the pesto and spoon on the glazed walnuts.Note: if necessary, loosen the pesto by stirring in a little water.