Use gloves whenever touching nettle leaves before they're cooked. Rinse nettle leaves thoroughly under cold water to get rid of any insects, using gloves. Bring a large pot of water to a rolling boil, add a couple tablespoons of salt. Add the nettle to the boiling water and stir to ensure the leaves are covered in the water. Boil for 1 minute, then drain and rinse with cold water.
Grab a handful of the nettle leaves and squeeze them over a bowl to catch excess water. Repeat with all the cooked nettle to press out as much water out as you can. Discard the water, keeping the cooked nettle leaves.
Working in 2 batches with half of the ingredients, pulse all the ingredients except the olive oil inside the bowl of a food processor until coarsely chopped, 6 to 8 times. Then with processor running, add olive oil in a thin steady stream until smooth and combined. Distribute the pesto between jars, then repeat with the remaining half of the ingredients and distribute that between the jars, as well.
Pour a tablespoon of olive oil on top of each of the pesto jars and then seal them with their lids. Use a piece of masking tape and a pen to label the lid with the current date, then place the jars upright in the freezer.
To thaw, place the jar in the refrigerator overnight.