01 - Set the oven to 350°F and allow it to reach temperature.
02 - In a large mixing bowl, blend cream cheese, sour cream, and mayonnaise until smooth and creamy.
03 - Add Parmesan, mozzarella, minced garlic, chopped spring onions, salt, pepper, and nutmeg; mix evenly.
04 - Gently fold the well-drained spinach into the mixture until fully combined.
05 - Transfer the mixture to a baking dish, spreading it out evenly.
06 - Bake for 20 minutes or until the dip is hot, bubbling, and lightly golden on top.
07 - While baking, place sourdough bread cubes or slices on a serving platter.
08 - Serve the warm spinach dip immediately alongside the sourdough bread.