Preheat your oven to 375°F (190°C). Lightly grease a 9-inch cast-iron skillet or an oven-safe 1.5-quart baking dish with nonstick spray or a drizzle of olive oil.

Wrap the thawed spinach in a clean kitchen flour-sack towel or paper towels and wring forcefully over the sink until no excess water remains. Ensuring the spinach is dry prevents a watery dip.

In a large mixing bowl, beat the softened cream cheese, sour cream, mayonnaise, minced garlic, salt, and black pepper with a wooden spoon or spatula until velvety and completely smooth.

Fold in the squeezed dry spinach, chopped artichoke hearts, 1 cup of the shredded mozzarella, and 1/4 cup of the grated Parmesan cheese until evenly distributed.

Transfer the mixture into your prepared baking skillet, smoothing the surface with a spatula. Sprinkle the remaining 1/2 cup mozzarella and 1/4 cup Parmesan cheese over the top, plus a pinch of red pepper flakes.

Bake uncovered for 20 to 25 minutes, until the edges are vigorously bubbling and the cheese is fully melted.

Switch the oven to broil on HIGH for 2 to 3 minutes, watching closely, until the top develops gorgeous golden-brown blistered spots.

Remove carefully and allow to cool for 5 minutes before serving alongside warm tortilla chips, toasted baguette slices, or fresh sliced crudités.