Preheat your oven to 180°C (350°F) and place a cast-iron skillet inside to warm up.
Melt the butter in a skillet over medium heat, letting it sizzle slightly as it melts and releases a rich aroma.
Add the minced garlic and cook for about 30 seconds until fragrant, stirring constantly. You should see it turn a light golden color.
Stir in the chopped cooked spinach and cook for 1-2 minutes until heated through and combined with the garlic and butter. The mixture will darken slightly and smell earthy.
Add the chopped artichoke hearts and cook for another minute, stirring to distribute evenly.
Mix in the cream cheese, stirring until it melts completely into the mixture, creating a creamy base.
Stir in the grated Parmesan and shredded mozzarella, blending until the cheese is fully melted and the dip is smooth and cheesy.
Season with salt, pepper, and red pepper flakes if using, tasting and adjusting as needed. The mixture should be flavorful and balanced.
Carefully transfer the hot mixture to the preheated cast-iron skillet, spreading it into an even layer with a spatula.
Bake in the oven for 20-25 minutes until bubbling around the edges and the top is golden brown with a crispy crust.
Remove from the oven and let sit for 5 minutes to settle and cool slightly. The dip should be hot, bubbly, and inviting.
Serve warm directly from the skillet with bread, pita chips, or veggie sticks for dipping. Enjoy the creamy, cheesy goodness with a crispy edge!