Warm the oil a ten inch saute pan or skillet over medium heat. Add the mushrooms and cook until starting to brown, then add the garlic and a drizzle of oil if the pan seems dry. Cook for a minute, stirring occasionally.
Add the white wine and reduce by half, then the cream.
Bring a large pot of salted water to a boil and cook the gnocchi for 2-3 minutes, or until they float. Remove the gnocchi with a slotted spoon to the pan with the sauce, toss, reduce the heat and cook until just thickened.
Turn the heat off, stir in the truffle butter and/or truffle oil, along with a tablespoon or two of parmesan cheese, taste the seasoning and adjust as needed, then serve. Garnish with fresh sliced truffle or shaved black truffle if you have some, along with grated parmigiano reggiano cheese. Chopped chives make a nice garnish too.
Video
Notes
Truffle substitutes
Here I use a combination of homemade truffle butter and oil, but you can use either or. If you want to use truffle oil, start with 2 teaspoons. You can also use truffle pate or paste or canned truffles in oil (1 Tablespoon for two servings) Avoid using truffle salt, or canned truffles as they don't have much flavor.Truffles and truffle products vary in intensity, so add them until the sauce tastes good to you. If you use fresh truffles, cut ½ oz black truffle into thick strips and add the to the pan at the very end of cooking, saving extra for garnishing.