Preheat oven to 375°F (190°C). Place the thawed chopped spinach into a clean kitchen tea towel or multiple layers of cheesecloth. Wring and twist the towel vigorously over the sink to squeeze out all excess liquid. You should extract at least 1/2 to 3/4 cup of green water. Fluff the dry spinach with a fork.

In a 10-inch cast iron skillet set over medium-low heat, add 1 tablespoon of olive oil and the minced garlic. Sauté gently for 60 seconds until fragrant without browning.

Add the softened cream cheese, sour cream, and mayonnaise. Stir with a wooden spoon until the cream cheese melts into a smooth, glossy sauce.

Fold in the squeezed dry spinach, chopped artichoke hearts, lemon juice, red pepper flakes, kosher salt, black pepper, 1 cup of shredded mozzarella, and 1/4 cup of parmesan. Stir until the cheeses melt and stringy ribbons form throughout the mixture.

Smooth the top of the dip evenly in the skillet. Scatter the remaining 1/2 cup of mozzarella and 1/4 cup of parmesan evenly over the entire surface.

Transfer the skillet to the preheated oven and bake for 18 to 20 minutes until the dip is hot and bubbling vigorously along the edges. Switch the oven to Broil on HIGH for 2 to 3 minutes until the cheese crust develops golden-brown blistered spots.

While the dip bakes, arrange the sourdough baguette slices on a baking sheet. Brush both sides with garlic herb melted butter. Toast in the oven for 8 minutes until crunchy and golden.

Carefully remove the bubbling hot cast iron skillet from the oven using thick oven mitts. Garnish with chopped fresh parsley and an extra pinch of red pepper flakes. Serve immediately surrounded by warm garlic bread soldiers, baguette rounds, and tortilla chips.