Preheat the oven to 400°F.

How to make freshly grated parmesan powder: Cut up a chunk of parmesan and chop the morsels in a mini-food processor until it's a fine powder. Gather about 8 tablespoons and reserve the rest for garnish later. Set aside.

For the dried porcini mushrooms: Put the dried mushrooms in a bowl and pour a cup of boiling water over them. Soak until softened, about 20 minutes. Remove the mushrooms, reserving the soaking liquid, and coarsely chop them.

For the walnuts: To release all the flavor and oil of the nuts, roast the walnuts in the oven for about 10 minutes at 325°F before using them. Chop the nuts. Reserve 1/3 cup for garnish. Grind the rest of the walnuts in a food processor or spice grinder. Make sure you stop before it turns into walnut butter. Set aside.

For the pasta: Bring about 8 quarts of water to a boil. Add the pasta shells, bring back to a boil, then immediately lower the heat to a gentle boil. That way the pasta is cooked all the way through evenly. Cook the pasta for about 12 minutes total. Salt (with 2/3 teaspoon) the water half-way through the cooking process (it will bring out the natural flavor of the pasta and the pasta will be more tender) and keep stirring every now and then so the pasta doesn't stick to the bottom. It may take longer than the cooking time that's written on the box. When the pasta is cooked (cooked inside and out but still in shape and firm), transfer it to a large flat platter. Season with the 1/3 teaspoon of salt.

For the pink sauce: It's the same procedure as the white sauce for making my cherry tomato tartlet. In a saucepan, melt the butter over medium-low; you don't want the butter to burn. Bring the heat back up to medium-high (the butter should be hot and golden) and add the flour. Keep stirring manually with a whisk for approximately 3 minutes. The flour should absorb the butter instantly and form a paste. Add the milk in 3 stages. Increase the heat while constantly stirring for about 5 minutes. Reduce the heat to low. Season with 1/2 teaspoon of sea salt and 1/3 teaspoon white pepper. Add 2 tablespoons of parmesan powder, the reserved porcini liquid and 1/3 the jar of tomato sauce. Stir well. Let the sauce rest until it's time to assemble the dish.

For the porcini mushroom walnut pesto: In a food processor or a mini-food processor if you have one, mix 2 tablespoons of parsley, the tarragon, soaked porcini mushrooms, oregano, ground walnuts, olive oil, walnut oil, garlic, 4 tablespoons of parmesan powder, lemon juice, 1/2 teaspoon of sea salt and 1/3 teaspoon of white pepper. Add about 2 tablespoons (or more) of water for a smooth flow. Set aside.

For the mushroom stuffing: In a sauté pan, heat the canola oil. Fry the onions in the oil, stirring frequently to prevent them from burning, until the color is evenly golden brown. Add the cremini mushrooms and the red chili flakes, then lower the heat. Add a tablespoon of curly parsley. Stir in about 3 tablespoons of walnut pesto and about 2-3 tablespoons of the pink sauce and cook for about 2-3 minutes.

Assembly time: In a 14” x 10” x 3” high rectangular pan lined with aluminum foil and sprayed with oil (for easy clean up), pour the rest of the jar of tomato sauce. Stuff the shells with the mushroom mixture and place the stuffed pasta shells into the pan. Ladle the pink sauce over the pasta shells. It should cover the whole pan. Sprinkle the remaining parmesan cheese.

Place in the oven and bake for 25-30 minutes at 375°F (until golden brown).

When it's cooked, remove from the oven and let rest for at least 20 minutes. Garnish with curly parsley and the remaining roasted walnuts. Finish with some white pepper.

Bon appétit!