Heat oven to 400°F (200°C) and lightly oil a 1½-quart baking dish. Seal the garlic cloves and 1 teaspoon olive oil in a foil packet and bake for 18–20 minutes until a fork slides through easily. Cool for 5 minutes. In a small bowl, combine panko, 1 tablespoon olive oil, and ½ teaspoon lemon zest and set aside.
Warm 2 teaspoons olive oil in a wide skillet over medium heat. Add the pressed spinach and chopped artichokes and cook for 4–6 minutes, stirring, until the pan stays dry when a spatula is dragged through. Cool for 5 minutes.
Mash the roasted garlic in a medium bowl. Add the softened cream cheese and Greek yogurt and stir until smooth with no large lumps. Stir in lemon juice, remaining ½ teaspoon lemon zest, onion powder, salt, and pepper.
Fold in the cooled vegetables, 150 g mozzarella, and 75 g white cheddar. Spread the mixture into the prepared baking dish without compacting it. Scatter the reserved 50 g mozzarella and 25 g cheddar over the surface, then sprinkle the panko topping in a thin, even layer.
Reduce oven to 375°F (190°C) and bake uncovered for 22–25 minutes, until the edges bubble and the center reaches 165°F (74°C). If the crumb needs more color, broil for 1–2 minutes, watching constantly.
Rest for 8 minutes before serving so the dip holds on a scoop.