Preheat your oven to 375°F (190°C). Lightly grease an 8-inch or 9-inch cast iron skillet or oven-safe baking dish with nonstick cooking spray or olive oil.

Place thawed spinach into a clean kitchen towel or several layers of paper towels and wring forcefully over the sink until every drop of excess moisture is removed. Coarsely chop the drained artichoke hearts into bite-sized chunks.

In a large mixing bowl, beat together softened cream cheese, sour cream, mayonnaise, minced garlic, fresh lemon juice, kosher salt, black pepper, and crushed red pepper flakes until completely smooth and velvety.

Add the squeezed dry spinach, chopped artichoke hearts, 1 cup of shredded mozzarella, and 1/4 cup of grated parmesan to the creamy base. Fold gently with a sturdy spatula until thoroughly combined and evenly distributed.

Spread the mixture evenly into the prepared cast iron skillet. Scatter the remaining 1/2 cup mozzarella and 1/4 cup parmesan cheese over the top. Bake uncovered at 375°F for 20 minutes until bubbling around the edges. Switch the oven to BROIL on HIGH for 1 to 2 minutes until the top cheese is golden-brown and blistered. Remove carefully, garnish with fresh parsley, and serve warm with toasted crostini or tortilla chips.