Blanch the Kale: Bring a large pot of well-salted water to a boil. Wash and destem the kale. Add the kale leaves to the boiling water and blanch for 4 minutes. Remove the leaves and run under cold water to stop the cooking process. Reserve the boiling water in the pot.
Cook the Pasta: Return the water to a boil and cook the pasta according to package instructions until al dente. Drain well.
Prepare the Kale: Squeeze excess water from the blanched kale and chop finely.
Combine the Salad: Add the drained pasta to a large bowl. Stir in the chopped kale, kale pesto, diced mozzarella, lemon juice, chopped olives, and roasted cherry tomatoes and onions. Toss well to combine.
Season and Serve: Add salt and freshly ground black pepper to taste. Serve immediately, or refrigerate and enjoy later once the flavors have melded.