Melt the butter in a small saucepan over low heat. Add the crushed garlic and half the sage leaves, and let them sizzle gently for 3 to 4 minutes until fragrant. Discard the garlic and sage, then set the butter aside.

Peel the potatoes and slice them 2-3 mm thick with a mandoline or sharp knife, keeping the slices even so they cook at the same rate.

Whisk the buckwheat flour, all-purpose flour, milk, salt, and a few grinds of black pepper in a mixing bowl until smooth and pourable, about the thickness of heavy cream.

Heat the oven to 200 C / 390 F. Butter a 26 cm / 10-inch springform pan and dust it lightly with buckwheat flour.

Arrange half the potato slices in the base of the pan, overlapping slightly like fish scales.

Pour half the batter evenly over the potatoes, scatter half the sliced Casera cheese on top, and drizzle with half the sage butter.

Repeat with the remaining potatoes, batter, and Casera cheese, finishing with the remaining sage butter and the reserved sage leaves tucked into the top layer.

Sprinkle the grated Grana Padano over the top.

Bake for 40 to 45 minutes, until the top is deep golden and blistered and a knife slides through the potatoes with no resistance.

Let the cotizza rest in the pan for 10 minutes before releasing the springform ring. Slice into wedges and serve warm.