Dry roast the cashew nuts and dry until they are golden and then transfer to a cool container immediately (or they will keep cooking on the hot frying pan).
Put parsley, parmesan, cashew nuts, garlic cloves, salt and pepper into a food processor and whiz into a paste.
If you like your pesto chunky then whizz for a shorter time than you would if you want it smoother.
Transfer paste into a container and slowly drizzle in olive oil mixing all the time till pesto is saturated. I added in about 50mls for this amount which is more than normal. But I was using an outdoor growing parsley that was a bit tough. If you have softer parsley you might use less oil.
Adjust seasoning and set aside.
Slice the mozzarella and tomatoes and arrange them in a salad bowl.
Top with the pesto and a drizzle of olive oil and serve with some warm crusty bread.