Bring a large pot of water to a boil. Add pasta to the boiling water and cook according to the package directions. Drain pasta in a colander saving a quarter cup of the cooking liquid..
While pasta is cooking, add butter, olive oil, garlic or garlic powder, and red pepper flakes to a large skillet. Cook over medium heat for 2–3 minutes or until the garlic is soft and fragrant.
Add kale and continue to sauté until the kale wilts and turns a deep green color (about 5–7 minutes). Turn heat off.
Add drained pasta and 2–4 tablespoons of reserved cooking liquid to the pot with the cooked kale. Toss the pasta and kale together.