These gnocchi are a variation on a Piedmontese specialty which goes by the name Cabiette. Some recipes call for grating the potatoes while they are raw and combining them with spinach (or more traditionally, nettles) and rye flour. I prefer boiling and ricing my potatoes because the texture is smoother and the gnocchi lighter. Either way, what gives this dish its distinct personality is the use of rye flour and topping of crispy rye bread crumbs, which give the gnocchi a pleasantly nutty flavor and marry well with the slight bitterness of the greens. If you can find nettles, pick off the tender leaves wearing gloves to protect your hands, discarding the stems.
The gnocchi can be boiled and topped with the caramelized onions, grated cheese, and bread crumbs up to 12 hours ahead and refrigerated, so this is a great make-ahead dish for entertaining. Just pop them into the preheated oven when you are ready to serve.
For the gnocchi:
- 1 and 1/4 pounds Yukon Gold potatoes
- 8 ounces fresh spinach leaves
- 4 ounces ( 1 and 1/4 cups) unbleached all-purpose flour, plus extra for the counter and trays
- 1 ounce rye flour (1/3 cup), or additional all-purpose flour if preferred
- ½ teaspoon salt
- ½ teaspoon freshly ground black pepper
For the sauce:
- 1 slice stale rye bread
- 1/2 teaspoon salt
- 2 tablespoons unsalted butter, plus extra for greasing the baking dish
- 1 pound yellow onions, thinly sliced
To cook the gnocchi:
- 2 tablespoons salt
- 1/4 pound Toma delle Langhe, Fontina, or Raclette, rind removed, grated
Make the gnocchi: Place the potatoes in a pot of cool water to cover and bring to a boil. Cook until tender when pierced with a knife, about 25 minutes. Remove to a tray and reserve the cooking water.
Pass the potatoes through a ricer onto a counter and allow to cool to room temperature (if you make the gnocchi while the potatoes are still hot, they will “sweat” and require additional flour, making them heavy rather than light).
Return the potato cooking water to a boil. Add the spinach and cook until tender, about 3 minutes. Drain, discarding the cooking water. Squeeze VERY DRY with your hands and chop finely.
Bring 1 quart of water to a boil.
On a counter, combine the riced potatoes, chopped spinach, all-purpose flour, rye flour, salt, and pepper. Gather gently into a dough; if the dough is sticky, add more all-purpose flour; if it is dry, add a touch of water. (Remember: you can always add flour, but you can never take it away, so be cautious when adding flour.) Don’t knead the dough, as the potatoes are naturally moist and they will make the dough feel sticky.
When the dough seems to be of the right texture, snip off a piece and test it in the boiling water: drop it in the boiling water until it floats to the surface, remove with a slotted spoon, taste, and adjust the texture of the gnocchi as needed, adding a bit more flour if they are too soft and falling apart, or a bit of water if they are too dry.
Shape the gnocchi: Roll the dough into 1-inch wide logs on a lightly floured counter and cut into 1-inch pieces. Arrange in a single layer on a lightly floured tray.
Make the sauce: Process the bread into crumbs into fine bread crumbs in a food processor; toss with 1/4 teaspoon of the salt and set aside.
Melt 1 tablespoon of the butter in a 12-inch nonstick skillet, add the onions, and season with the remaining 1/4 teaspoon of salt. Cook until caramelized, stirring often, about 25 minutes over medium-low heat; set aside.
Melt the remaining tablespoon of butter in a small pan and keep warm. Butter a large baking dish and set it aside.
Cook the gnocchi: Preheat the oven to 325° (preferably set on convection). Bring 4 quarts of water to a boil. Add the salt.
Drop in the gnocchi and cook until they float to the surface. Remove with a slotted spoon to the buttered baking dish.
To bake: Top with the caramelized onions, and pour on the melted butter. Scatter the Toma over the gnocchi and top with the rye bread crumbs. Bake for 10 minutes, or until the cheese has melted and the bread crumbs are golden, and serve hot.