This is truly easy and can be prepared in advance.
4 Tablespoons butter at room temperature
8 oz. mushrooms, finely chopped
1 ½ teaspoons finely chopped shallot
¼ cup finely chopped green onions, white parts only
1/3 cup chicken stock
4 oz. cream cheese at room temperature
2 Tablespoons finely minced fresh chives
Salt and freshly ground pepper to taste
1 teaspoon chopped chives (or green tops of scallions for garnish)
Melt 2 Tablespoons of the butter in a medium skillet over medium-high heat. Add chopped mushrooms and sauté for ~ 3 minutes. Add shallots and chopped green onions and sauté 1 more minute. Add chicken stock and cook over high heat until all liquid has evaporated. ~ 4 to 5 minutes. Let mushroom mixture cool to room temperature.
Combine the cream cheese and remaining 2 Tablespoons of butter in a mixing blow and stir to mix well. Add the cooled mushroom mixture, minced chives, salt, and pepper. Mix well.
Fill a 1-cup ramekin or small soufflé dish with the mushroom mixture. Cover with plastic wrap and refrigerate.
The mushroom mousse can be made a day in advance.
Sprinkle with chopped chives as a garnish when ready to serve. Serve with crackers of your choice or thin slices of baguette.