I've made different variations on this pesto depending on what greens I have on hand. In addition to kale, I have made it with Swiss chard, collard greens, broccoli leaves, and beet greens. Blanching green vegetables like kale, broccoli leaves, and beet greens ever so briefly removes the chalky taste. If you make it with collard greens (stems/veins removed), you'll need to cook it longer, approximately 15 minutes. This pesto will have a bit of a chew to it, so if you like a lighter pesto, add more basil.