Preheat the oven to 375°F.
Thaw the frozen spinach in the microwave (or at room temp) and drain out the excess liquid.
In a large bowl, combine the artichokes, garlic, spinach, cream cheese, sour cream, mayonnaise, parmesan, mozzarella, salt, pepper and lemon juice; spread the mixture into a cast iron or baking dish.
Toast the panko in a pan over medium heat with butter and a pinch of salt until they are golden brown.
Sprinkle parmesan and toasted panko on top of the dip and bake for 20-25 minutes until the cheese on top is melted and bubbling; serve with chips or sliced veggies.
