Heat olive oil in a large skillet over medium-high heat. Once hot, add the onion and cook for 2-3 minutes, then add the garlic and cook for 2 minutes more.
Add the artichoke hearts and lemon zest, cooking for another 2 minutes, then add the spinach and seasonings. Once the spinach has wilted, mix in the cream cheese and yogurt until everything is well coated.
Stir in the Parmesan cheese, then remove from heat. Top with an even layer of mozzarella cheese.
Transfer the skillet to the oven and set it to BROIL. Place the pan on the low or medium rack and broil for 3-4 minutes until the top is nicely browned—keep a close eye on it to prevent burning.
Remove from the oven, dig in, and ENJOY!!!