Bring a large pot of water to a boil. Submerge the kale in the boiling water and cook for just one minute. Drain in a colander and rinse in cold water. Squeeze out the excess water.
In a small skillet over medium heat, lightly toast the walnuts until fragrant and lightly golden, about 3 minutes. Remove from pan and set aside.
Place the kale, toasted walnuts, parmesan, garlic, and parsley in the bowl of a food processor. Sprinkle with salt and pepper, and process until the walnuts are finely chopped. While the food processor is running, add the oil in a steady stream and process until smooth, adding more oil, a bit at a time, if needed. Taste, and add more salt and pepper if needed.
Toss with pasta, or use however you would normally use pesto.