How to Make It
In a large skillet, melt the butter in 1 tablespoon of olive oil. Add the shiitake and cook over moderately high heat, stirring, until browned, 4 minutes. Add the oyster mushrooms and cook until softened and lightly browned, 4 minutes. Add the shallot and garlic and cook until fragrant, 2 minutes. Stir in the wine, lemon juice, thyme and the 1 tablespoon of parsley. Season with salt and pepper.
Light a grill or preheat a grill pan. Brush the bread with olive oil and grill until toasted and charred in spots, about 1 minute per side.
Spread each toast slice with 1/4 cup of the ricotta. Spoon the mushrooms on top and and sprinkle with the tarragon, chives and additional parsley. Cut the crostini in half, drizzle with olive oil and serve.