Roast the Garlic:
Preheat oven to 400°F (205°C).
Peel garlic cloves, wrap them in foil with a splash of veggie broth, and roast while cooking the veggies.
Cook the Vegetables & Cashews:
In a pot, add potatoes, yellow pepper, carrots, onion, and cashews. Cover with water.
Bring to a boil over high heat (about 15 minutes). Reduce to medium heat and cook for another 20 minutes until potatoes are tender.
Drain, reserving some cooking water for thinning the sauce.
Blend the Sauce:
Place cashews in a blender, followed by the measured amount of each cooked vegetable.
Add roasted garlic, apple cider vinegar, mustard seed powder, chickpea miso, and sea salt.
Blend on high until smooth and creamy. Adjust mustard seed for a sharper taste.
If needed, add reserved cooking water, 1 tablespoon at a time, until desired consistency is reached.
Use for Mac and Cheese:
Cook pasta according to package instructions. Drain, reserving 1 cup of pasta water.
Return pasta to the pot, stir in the cheese sauce, and mix well.
Add pasta water (or non-dairy milk) 1 tablespoon at a time until the desired consistency is reached. Adjust salt if needed.