For the Lemon Cashew Cream:
For the Pasta:
Cook pasta in a large pot of salted boiling water until al dente. Drain, reserving 1 cup of the cooking liquid. Meanwhile, make the Lemon Cashew Cream by blending all the ingredients in a high-speed blender until smooth. Set aside.
In a large skillet, heat the oil over medium-high heat. Add the spring onions and the asparagus. Season with salt and cook, stirring, until just beginning to take on color, about 3 minutes. Add the garlic, the lemon zest and red chili flakes, and cook 1 minute more. Add the lemon cashew cream, the lemon juice, the pasta, and stir well until well-coated, adding some of the pasta cooking liquid, as needed. Add 3 tablespoons of the fresh basil and season to taste with sea salt and pepper. Divide among bowls and top with remaining fresh basil. Bon appétit!