1. Preheat your oven to 375°F (190°C). Lightly grease a 9×9-inch baking dish with butter or olive oil.
2. If using fresh spinach, rinse thoroughly and sauté in a skillet with olive oil and minced garlic over medium heat until wilted, about 3-4 minutes. Drain excess moisture by pressing spinach in a sieve or with paper towels. If using frozen spinach, make sure it’s fully thawed and squeezed dry.
3. In the same skillet, sauté the chopped onion in a bit of olive oil or butter until translucent, roughly 4 minutes. This step brings out the sweetness that Mama Lou always said “makes the dish sing.”
4. In a large mixing bowl, combine the softened cream cheese and sour cream until smooth. I like to use a hand mixer for this step to avoid lumps and keep it silky.
5. Add the sautéed spinach, onions, chopped artichoke hearts, garlic, salt, pepper, and red pepper flakes (if using) to the cream cheese mixture. Stir gently to combine all the flavors evenly.
6. Fold in half of the mozzarella and all of the Parmesan cheese, saving the other half of the mozzarella for the topping.
7. Transfer the mixture to the prepared baking dish and spread evenly. Sprinkle the remaining mozzarella cheese on top for that beautiful golden crust.
8. Bake uncovered for 25-30 minutes or until the casserole is bubbly and the cheese on top is golden brown. You’ll know it’s ready when you see those delicious browned edges and smell the aroma filling your kitchen.
9. Let the casserole rest for about 5 minutes before serving. This helps it set and makes it easier to scoop out.

One of my favorite memories is how Mama Lou would let Ouma and me sneak tastes off the spoon while the casserole baked. That warm, cheesy mixture was our little secret until dinner was served.