Preheat oven to 350 degrees F.
Arrange baguette slices on a baking sheet and lightly toast in the oven.
Allow bread to cool down and spread goat cheese, to taste, on each piece.
In a medium skillet, heat olive oil over medium high heat. Add the mushrooms and sauté, 3-5 minutes.
Add garlic and continue cooking another minute or so.
Add wine and balsamic vinegar. Stir while liquids are reduced slightly.
Stir in scallions and remove from heat.
Top each crostini with mushroom mixture and serve warm.