Heat oil in a large skillet over medium heat.
Cook garlic and pepper flakes until fragrant, stirring frequently, approx. 30-45 seconds.
Add kale, and stir until slightly wilted.
Remove from heat and stir in walnuts, lemon zest and juice.
Season with salt and pepper.
Meanwhile, cook pasta in well-salted water according to package directions.
Once done, reserve 1/2 cup pasta water and drain.
Add pasta to skillet, tossing to coat.
Add reserved water as needed to reach desired consistency
Sprinkle with cheese before serving.