Preheat your oven: Start by preheating your oven to 375°F (190°C).

Prepare the spinach: If you're using fresh spinach, give it a quick chop and then steam it until wilted. If you're using frozen spinach, make sure it’s thawed and very well-drained. Excess water will make the dip too runny.

Mix the base: In a large mixing bowl, combine the softened cream cheese, sour cream, and mayonnaise. Use a hand mixer or a sturdy spoon to blend until smooth.

Add the veggies and seasonings: Fold in the chopped artichoke hearts, spinach, minced garlic, salt, black pepper, and red pepper flakes if you’re using them.

Incorporate the cheeses: Add in the grated Parmesan and the shredded mozzarella, stirring until everything is well combined.

Transfer to baking dish: Spoon the mixture into a medium-sized, oven-safe baking dish. You can sprinkle a bit of extra mozzarella on top if you want a nice, melty layer.

Bake: Place the dish in the preheated oven and bake for 25-30 minutes, or until the dip is hot and bubbly with a golden-brown top.

Serve hot: Remove from the oven and let it cool for a minute or two before serving. Pair it with your favorite chips, crackers, or even some fresh veggie sticks.