Preheat the broiler and line a baking sheet with parchment paper. Heat the olive oil in a saute pan over medium-high heat.
Add the whites of the green onions, garlic, thyme, and saute until they are a light golden brown.
Add the mushrooms, and saute until golden brown. Drizzle in the soy sauce, and continue cooking, stirring for 1 minute.
Sprinkle in the chopped green onion tops, season with salt, and pepper, to taste, and remove the pan from the heat. Transfer the mushroom mixture to a bowl, and allow the dish to cool.
Fold the goat cheese into the mushroom mixture. Arrange the toasted baguette slices on the prepared baking tray, and top with a spoonful of the mushroom mixture. Broil the bruschettas in the preheated oven, until the cheese has softened, approximately 3 minutes.