1 large bunch Tuscan kale, ribs and stems removed
sea salt
⅓ cup raw pistachios
¼ cup extra-virgin olive oil
1 garlic clove
freshly ground black pepper
1 ounce Parmesan, finely grated
2 tablespoons unsalted butter, softened to room temperature (optional)
*Freezing pesto: Make pesto through to the end of Step 2, cover with a thin layer of olive oil and freeze it without the cheese and butter. Add the cheese and butter when it is thawed, just before serving.