Preheat the oven to 400°F and line a baking sheet with parchment paper.
Make the dressing first. In a small bowl, stir together ¼ cup Caesar dressing and ¼ cup Greek yogurt. Add ¼ teaspoon garlic powder, 1 teaspoon lemon juice, ⅛ teaspoon salt, and ⅛ teaspoon black pepper. Taste and adjust — if it's too tangy from the yogurt, add a little more Caesar. If it tastes too heavy, add more yogurt. Grate in 1 tablespoon parmesan if it needs more depth.
Spread ½ cup shredded mozzarella into a circle on the parchment, roughly the size of a small dinner plate (about 7–8 inches across). Press 6 pepperoni slices evenly across the top.
Bake for 12-15 minutes, until the edges are golden brown and the cheese looks crisp.
Pull it out and let it sit for 2–3 minutes. This is the part most people skip — it has to firm up before you move it or it'll fall apart.
While it cools, toss 2 cups chopped romaine and ½ cup chopped rotisserie chicken with the dressing in a bowl. Add 2 tablespoons grated parmesan and ¼ cup croutons if using.
Carefully flip the cheese shell over, pile the salad onto one half, and fold it like a taco. Eat immediately while the shell is still crispy and the salad is still cold.