01 - Preheat the oven to 350°F.
02 - In a large mixing bowl, blend the cream cheese, sour cream, and mayonnaise until smooth.
03 - Stir in Parmesan, mozzarella, minced garlic, spring onions, salt, pepper, and nutmeg until fully combined.
04 - Gently fold the well-drained spinach into the mixture, ensuring even distribution.
05 - Spread the prepared dip evenly in a baking dish.
06 - Bake for 20 minutes or until the dip is hot, bubbling, and lightly golden on top.
07 - While baking, arrange sourdough bread cubes or slices on a serving platter.
08 - Serve the warm spinach dip immediately alongside the sourdough bread for dipping.