Easy Vegan Spinach Pesto Pasta

Bring a pot of generously salted water to a boil, and cook your pasta according to package directions. Drain it, reserving ½ cup of the cooking water. Do not rinse.Add the cashews to your food processor and pulse a few times until crumbled.Add the spinach, basil, nondairy milk, lemon juice, salt, and pepper, and continue to pulse, stopping to stir and scrape the sides if needed, until the spinach and basil are finely chopped.Add more lemon juice to taste if desired, and set aside.In a large pan, heat olive oil over medium heat. Add the onion or shallot and a sprinkle of salt. Continue to cook, stirring occasionally, until the onion is softened and browning slightly.Add the cooked pasta, reserved pasta water, and pesto and fold everything together gently. Reduce the heat to medium-low and cook, stirring frequently, until the sauce has thickened slightly and clings to the pasta, and is warm throughout. Remove from the heat and adjust seasoning to taste. Serve warm. The pasta is best eaten immediately; fold in a light drizzle of olive oil before storing leftovers and keep in the fridge for up to 3 days.