Kosher Cannelloni Ragù and Spinach

Here's how to cook kosher cannelloni with spinach and bolognese sauce in 3 easys steps:

For the filling, chop the onion, carrot, and celery. Heat the oil in a skillet over medium heat and sauté the vegetables until lightly browned. Add the lentils and brown. Add the white wine, raise the heat to high, and cook until wine is completely evaporated. Add the spinach, season with a pinch of salt and a dash of pepper, and continue cooking the mixture over medium heat for 15 to 20 minutes. Remove from heat and let the mixture cool to room temperature. Transfer to a food processor and pulse mixture. Add the egg, half of the grated Parmigiano Reggiano, and a pinch of nutmeg and pulse until thoroughly combined.

For the béchamel, melt the butter in a heavy-bottomed pan. To make a roux, add the flour and whisk butter and flour together for 3 to 4 minutes over low heat, until smooth. Heat the milk in a separate pan, then add to the roux, pouring it in a slow stream. Adjust the salt, season with a bit of nutmeg, and continue cooking, whisking constantly to avoid the formation of lumps, until the sauce is thick and creamy. If the béchamel is too thick, add a bit of milk. If it is too thin, let it cook for a few additional minutes.

Heat the oven to 375°F (190°C). Use a pastry bag to fill the cannelloni. Butter a 9-by-13-inch baking dish and arrange the filled cannelloni evenly in pan. Finish with a uniform layer of béchamel, dusting it with the remaining cheese, and dotting the top with the pieces of butter. Bake the cannelloni for 15 to 20 minutes, until lightly browned. Remove them from the oven and let them rest for several minutes before serving.