Follow these detailed steps to guarantee a perfectly baked, bubbly, and delicious spinach artichoke dip every single time. The key to success lies in the preparation of the ingredients and the mixing technique.

1. Prepare for Baking: Begin by preheating your oven to 375°F (190°C). Lightly grease a 1.5-quart baking dish or a 9-inch pie plate with butter or non-stick cooking spray. This will prevent the dip from sticking and make cleanup much easier. Set the prepared dish aside.
2. The Most Crucial Step – Dry the Spinach: This step cannot be overstated and is the single most important secret to a thick, creamy dip versus a soupy, watery mess. Once your frozen spinach is completely thawed, you must remove as much liquid as possible. You can do this by placing the spinach in the center of a clean kitchen towel or several layers of heavy-duty paper towels. Gather the edges and twist, squeezing firmly over the sink until no more water drips out. You will be amazed at how much liquid is released. Alternatively, you can press the spinach into a fine-mesh sieve with the back of a spoon.
3. Prepare the Artichokes and Garlic: Open the can of artichoke hearts and pour them into a colander to drain away all the canning liquid. Gently pat them dry with a paper towel. Place them on a cutting board and give them a rough chop. You want noticeable pieces, not a fine mush. At the same time, peel and finely mince your fresh garlic cloves.
4. Create the Creamy Base: In a large mixing bowl, combine the softened cream cheese, sour cream, and mayonnaise. Using a hand mixer on low speed or a sturdy spatula, beat the ingredients together until the mixture is completely smooth, creamy, and well-combined. Ensuring the cream cheese is soft is vital here to avoid a lumpy base.
5. Incorporate Seasonings and Cheeses: Add the minced garlic, grated Parmesan cheese, freshly ground black pepper, and salt to the cream cheese mixture. Also, add half of your shredded mozzarella cheese (about 1/2 cup) to the bowl. Mix everything together until it’s evenly distributed. This method ensures that every bite of the dip is packed with flavor.
6. Fold in the Stars of the Show: Now, add the thoroughly squeezed spinach and the chopped artichoke hearts to the bowl. Switch to a rubber spatula and gently fold the spinach and artichokes into the cheese mixture. Be careful not to overmix; you want to fold just until everything is incorporated. This gentle folding keeps the texture of the main ingredients intact.
7. Assemble and Bake: Scrape the finished dip mixture into your prepared baking dish, using the spatula to spread it into an even layer. Sprinkle the remaining 1/2 cup of shredded mozzarella cheese evenly over the top. This top layer will melt into a beautiful, golden-brown, and bubbly crust.
8. Bake to Perfection: Place the dish in the preheated oven. Bake for 20 to 25 minutes, or until the dip is hot, bubbling around the edges, and the cheese on top is melted and lightly golden. For a browner, more blistered top, you can switch the oven to the broil setting for the last 1-2 minutes, but watch it very carefully as it can burn in an instant.
9. Rest and Serve: Carefully remove the dish from the oven and let it rest for at least 5-10 minutes before serving. This allows the dip to set up slightly, making it easier to scoop, and brings it down from a scorching hot temperature to a deliciously warm one.