3 pounds potatoes, peeled and cut into chunks
3 tablespoons unsalted butter
8 scallions, sliced, including the green tops
1/4 cup milk
1 cup shredded mozzarella
1/8 teaspoon pepper
½ teaspoon salt
3 tablespoons olive oil
1 large bunch spinach, washed and drained
½ cup chopped red onion
4 tablespoons plain bread crumbs
Grated parmigiano or pecorino romano
Bring a large pot of water to a boil. Add the potatoes and cook them until they are tender when pieced with a fork, about 10 to 12 minutes. Drain well and put them in a large bowl.
Melt the butter in a small pan. Add the scallions and sauté them over medium heat, stirring occasionally, until they are soft and lightly browned, about 5 to 7 minutes. Meanwhile, mash the potatoes well. Add milk, mozzarella, pepper, and half the salt. When the scallions are cooked, add them to the potato mixture and blend thoroughly. Set this aside.
Lightly brush the bottom and sides of a medium casserole or baking dish (preferably round or oval) with ½ tablespoon of the olive oil. Line the bottom and sides of the dish with the largest and best looking of the spinach leaves. Overlap them as necessary to cover the entire bottom.
Heat the remaining oil in a medium pan. Add the onions and sauté until soft and translucent, about 3 to 5 minutes. Add the chopped spinach and remaining salt and sauté until it is wilted, about 1 to 2 minutes.
Preheat the oven to 350 degrees F.
Spoon the potato filling into the spinach-lined dish and using your hands, carefully spread it out evenly and pack it down. Sprinkle the bread crumbs evenly over the potatoes. Cover the bread crumbs with the cooked spinach, spreading it out evenly with a spoon.
If any spinach leaves are sticking out of the sides from underneath, fold them over the top and brush them with a little olive oil so they don’t dry out.
Place the timbalo in the oven and bake until it is completely heated through, about 10 to 15 minutes. To serve the timbalo, place a large serving platter on top of the baking dish and carefully flip it over. Lift off the baking dish and sprinkle a little parmigiano or pecorino on top and serve hot.
Keep leftovers tightly sealed in the refrigerator up to 5 days.
Makes 4 to 6 servings.