1. Preheat oven to 400°F.
2. Chop artichoke hearts by hand (or use a food processor for a smoother dip).
3. In a large bowl, mix the artichoke hearts with 1 cup Parmesan cheese, 1 cup shredded mozzarella or 4-cheese blend, Greek yogurt, garlic, and lemon zest. Note that if you want a smooth dip, you can puree all the ingredients in a food processor; I personally prefer a chunky dip.
4. Transfer to a suitable sized baking dish (I use a round pie plate) and sprinkle with the reserved 2 tablespoons of grated Parmesan cheese.
5. Cover the dish with foil and bake until the dip is heated through and bubbly, about 20 minutes. You can uncover it for the last 5 minutes so it browns a bit on the top, if you like. Sprinkle with the optional smoked paprika or cayenne pepper, and serve warm with sliced baguette, pita bread, all natural chips or rice crackers, and/or raw vegetables.