When using dried porcini, soak them in hot water for around 15 minutes until they soften completely. Drain well before cooking, but keep the soaking liquid.
If cooking with fresh porcini, clean them carefully without rinsing them in water. Brush off any forest debris (bits of soil, leaves, or pine needles) with your hands or a soft brush.
Slice the porcini thinly. Finely chop the onion and either slice or crush the garlic. The finer you chop them, the creamier and smoother your sauce will be later.
Warm up a mix of olive oil and butter in a wide skillet or pan. Add the onion and garlic and cook slowly over medium-low heat until soft, golden, and fragrant. This step takes a few minutes but sets the base for a silky sauce. When ready, stir in the sliced mushrooms.
Season with salt, freshly ground black pepper, and a pinch of marjoram. Stir the mixture for a minute to help the mushrooms release their aroma, then pour in the wine.
Lower the heat and let it simmer gently for three to four minutes. The porcini will shrink, and their flavors will concentrate as the wine cooks down and the alcohol evaporates.
Pour in the cream and mix well so it combines evenly with the mushrooms. Continue cooking over low heat for another five minutes, just until the sauce thickens slightly. Stir in the chopped parsley right at the end.
Serve the porcini sauce warm and glossy - that’s when it’s at its best. It pairs beautifully with pasta, gnocchi, rice, meat, or even roasted vegetables. Once it cools, the consistency will change, so enjoy it fresh while the sauce is still soft and creamy.