Wash and dry spinach, then sauté over medium heat until wilted, 2–3 minutes. Cool and chop finely.

In a mixing bowl, combine sour cream, mayonnaise, and softened cream cheese until smooth.

Stir in Parmesan, garlic powder, salt, and pepper.

Fold in chopped spinach, green onions, and water chestnuts (if using) until fully combined.

Transfer to a serving bowl and refrigerate at least 30 minutes to meld flavors.

Serve with tortilla chips, crackers, or fresh vegetables.