Warm the milk until just steaming, then pour over the bread cubes in a large mixing bowl. Press down so all the bread is soaked and let sit for 15 minutes until soft.

Meanwhile, melt 20 g of the butter in the 8-inch / 20 cm skillet over medium heat. Add garlic and shredded savoy cabbage, season with salt, and cook 8-10 minutes, stirring, until wilted and just tender. Discard garlic and set the cabbage aside.

Mash the soaked bread with a fork until no large lumps remain. Mix in the eggs, buckwheat flour, all-purpose flour, 80 g of the Casera cheese, nutmeg, 1 tsp salt and a few grinds of pepper until you have a dough thick enough to hold its shape when pressed. If it feels too wet, add another tablespoon of buckwheat flour.

With floured hands, shape the dough into small gnocchi about the size of a walnut, roughly 20 g each. Set them on a floured tray as you go.

Bring the 5-quart / 4.7 L stockpot of salted water to a boil. Drop in the gnocchetti in batches so the pot isn't crowded, and cook until they float to the surface, about 3-4 minutes. Lift out with a slotted spoon and drain.

Heat the oven to 200 C / 390 F. Butter the 9x13-inch / 23x33 cm baking dish. Layer half the gnocchetti in the dish, scatter over half the cooked cabbage and a third of the remaining Casera. Repeat with the rest of the gnocchetti, cabbage, and another third of the cheese.

Melt the remaining 50 g butter in the skillet with the sage leaves until foaming and golden brown with a nutty smell, about 2 minutes. Watch closely, it turns bitter if it goes past golden. Pour over the gnocchetti.

Scatter the last of the Casera and the Grana Padano over the top. Bake for 18-20 minutes until the top is deep gold and the cheese is bubbling.

Rest 5 minutes before serving so the layers set enough to hold a spoonful.