Boil a large pot of salted water over high heat until rolling.

Blanch fresh spinach in boiling water for 1-2 minutes until bright green, then drain and squeeze out excess moisture.

Soak stale bread cubes in warm milk for about 10 minutes, pressing gently to fully saturate.

Sauté finely chopped onion in a tablespoon of butter over medium heat until translucent, about 4-5 minutes.

In a mixing bowl, combine squeezed spinach, soaked bread, sautéed onion, eggs, grated Parmesan, parsley, nutmeg, salt, and pepper. Mix well and let rest for 8-10 minutes.

Shape the mixture into golf-ball-sized dumplings, about 12 in total, packing gently.

Poach the dumplings in simmering salted water for 12-15 minutes until they float and feel firm.

Melt butter with fresh sage leaves in a small pan over low heat until foamy, then drizzle over cooked dumplings.

Serve hot with additional Parmesan and light cream sauce.