Preheat the oven to 400°F.

Bring a medium pot of salted water to a boil and set a bowl of ice water nearby. Add the spinach. Immediately use a slotted spoon to transfer it to the ice water. Let chill for 1 minute, then drain. Squeeze the excess moisture from the spinach and roughly chop.

Place the spinach in a medium bowl and add the artichokes and chives, reserving some chives for garnish.

In a high-speed blender, place the cashews, water, olive oil, lemon juice, nutritional yeast, garlic, salt, mustard, and onion powder. Blend until smooth and creamy.

Pour the creamy mixture over the spinach and artichokes and stir to combine. Season to taste.

Spread the dip in an 8-inch cast iron skillet and bake for 8 to 10 minutes, or until just warmed through. Remove from the oven, sprinkle with the reserved chives, and serve with toasted baguette.