In a large pot filled with salted water, boil the pasta to al dente (with a slight 'bite' to it). Drain and return pasta to the pot or a large bowl. Keep warm.
In a food processor or high powered blender, add cashews, salt and nutritional yeast. Blend until combined and resembling a powder (consistency will vary depending on strength of machine, but try and blend until powder-like). Set aside (keep in blender).
In a large skillet over medium-high heat, add vegetable broth, garlic, and onion. Cook for 4-5 minutes until onion is just starting to become translucent, stirring occasionally.
Reduce heat to medium. Stir in flour. Then slowly add unsweetened almond milk, nutmeg , and turmeric, and stir with a whisk until blended. Cook for 15-18 minutes over medium heat, stirring occasionally until mixture thickens.
Add the cashew powder and stir (no need to clean blender at this time), 1 can of green chiles, and the jalapeños. Stir to combine. Reduce heat to low and cook for 1-2 minutes, stirring constantly.
Remove from heat, and transfer the sauce to the blender and carefully process until blended, starting on low speed and increasing as you go.
Return the sauce to the pot, add the remaining 1 can of green chiles (if desired). *Rinse the blender immediately so it doesn’t stain yellow from the turmeric. Simmer the sauce over low-medium heat for 2 minutes, stirring.
This dish is best served fresh. If serving immediately, add the sauce to the cooked pasta and stir to blend. Note: there will be a lot of sauce but it will thicken over time. If you are not eating all of mac and cheese at one time, it’s best to store the sauce and pasta noodles separate, as the noodles absorb the sauce over time. To make in advance/storage instructions, see notes below.
Season with salt and pepper, or add a dash of cayenne pepper or lime juice, or chopped cilantro.