- 3 cups Alfredo sauce
- 1 clove garlic, finely grated
- 1 pinch kosher salt and freshly ground black pepper to taste
- 1/2 cup freshly grated Parmigiano-Reggiano cheese
- 1/2 cup freshly grated Pecorino cheese
- 2 1/2 pounds baking potatoes, peeled and sliced crosswise into 1/8-inch thickness
- 1/4 cup chopped fresh parsley, divided
- 6 ounces baked ham, sliced into 1/4-inch thickness and cut into 1/4-inch cubes
- Preheat oven to 400 degrees F (200 degrees C). Butter a 9×13-inch baking dish.
- Bring Alfredo sauce to a simmer in a saucepan over medium-low heat, about 5 minutes; add garlic, salt, and pepper. Reduce heat to low and keep sauce warm.
- Mix Parmigiano-Reggiano cheese and Pecorino cheese together in a bowl.
- Arrange 1/4 the potato slices in the bottom of the prepared baking dish, overlapping them slightly. Sprinkle 1/4 cup cheese mixture, 1 tablespoon parsley, and 1/3 the ham over potato layer. Repeat layering 2 more times, ending with a final layer of potatoes and 1/4 cup cheese mixture. Pour Alfredo sauce mixture over and around the potatoes.
- Bake in the preheated oven until potatoes are tender, sauce is bubbling, and top is golden brown, 25 to 30 minutes. Let potatoes cool for 15 minutes. Sprinkle remaining 1 tablespoon parsley over potatoes before serving.