RINSE the cashews and drain. Place the cashews in a bowl and add enough water to cover by 1 inch. Cover the bowl and let stand for 4 hours or up to overnight. Drain the cashews and rinse under cold water. Set aside.
PREHEAT the oven to 400°F. Line a large rimmed baking pan with parchment paper.
PLACE the potatoes in a large bowl. Drizzle with olive oil and sprinkle with the rosemary, thyme, ½ teaspoon salt, and ½ teaspoon pepper; toss to coat. Arrange in a single layer on the baking pan, cut sides down. Roast for about 25 minutes, until the potatoes are tender and bottoms are lightly browned.
MEANWHILE, combine the soaked cashews, mayonnaise, ½ cup of water, lemon zest and juice, nutritional yeast, garlic, and the remaining ½ teaspoon salt and ½ teaspoon pepper in a blender or food processor. Cover and pulse until finely chopped and then puree until smooth, about 2 minutes. Roughly chop the artichoke hearts. Add the artichokes and parsley to the blender or food processor. Cover and pulse until the artichokes and parsley are finely chopped. Transfer the mixture to a 9-inch glass pie plate.
BAKE for 25 to 30 minutes at 160°F, until the top is lightly browned and heated through. Serve hot with the potatoes for dipping.