Cook pasta according to package instructions in a pot of salted water. During final four minutes, add asparagus and peas. Reserve 1/2 cup pasta water before draining.
While pasta cooks, heat oil in large skillet over medium-low heat. Once warm, add garlic and chili flakes. Cook 4 to 5 minutes, until garlic is golden and aromatic. Sprinkle in flour; stir with a whisk until smooth. Cook 2 full minutes, stirring often, to eliminate raw flour taste.
Gradually stream in cashewmilk, whisking constantly, until mixture is smooth. Increase heat and bring mixture to a simmer; cook for 3 to 5 minutes, until sauce starts to thicken. Remove from heat and stir in salt, pepper, lemon zest and juice, and nutritional yeast.
Pour sauce into pot with drained pasta and veggies and stir to combine. If sauce is too thick, stir in some of the reserved pasta water in 1/2 cup increments until desired consistency is achieved. Stir in fresh basil and serve immediately with garnishes of choice.