
Blend the sauce. Preheat the oven to 400°F (200°C). Add the cashews, mayonnaise and water to a food processor. Blend for 1 to 2 minutes, until creamy.
Mix the dip. Transfer the cashew mixture to a large mixing bowl. Add the frozen spinach, artichoke hearts, onion, garlic, salt, and pepper. Stir to combine.
Bake the dip. Transfer the dip to a baking dish and bake for 20 minutes. Serve warm with tortilla chips, cucumber slices or other vegetables.