Thaw and Drain Spinach. Place the frozen spinach in a microwave-safe bowl and thaw according to package instructions. Once thawed, use a clean kitchen towel or paper towels to squeeze out as much excess moisture as possible.
Chop Artichokes. Drain the marinated artichoke hearts and chop them into bite-sized pieces for even distribution throughout the dip.
Mix Cream Cheese, Sour Cream, and Mayonnaise. In a large bowl, use a hand mixer or stand mixer to blend the softened cream cheese, sour cream, and mayonnaise until smooth and creamy.
Add Garlic and Spices. Stir in the minced garlic, red pepper flakes, salt, and pepper, ensuring the mixture is well-seasoned.
Fold in Spinach and Artichokes. Gently mix the drained spinach and chopped artichokes into the creamy base, ensuring an even distribution of ingredients.
Stir in Parmesan and Mozzarella. Combine the grated Parmesan cheese and shredded mozzarella into the mixture, blending until fully incorporated. The cheeses will melt into the dip, creating a luscious texture.
Pour the Mixture. Transfer the entire mixture into your crockpot, spreading it out evenly to ensure consistent heating.
Set the Crockpot. Cover and cook on low heat for 2-3 hours, stirring occasionally. The dip should be hot, bubbly, and the cheeses fully melted.
Optional: Add Extra Cheese. For an extra cheesy dip, transfer the dip to a baking dish and sprinkle additional mozzarella on top. Bake for 20 minutes at 350F.
Garnish and Enjoy. Once cooked, give the dip a final stir and transfer it to a serving dish. Garnish with a sprinkle of additional Parmesan cheese, red pepper flakes, or freshly chopped parsley for a pop of color.