Wild Mushroom Crostini

Name: Wild Mushroom Crostini
Ingredients: 1 tablespoon unsalted butter; Extra-virgin olive oil; 1/2 pound shiitake mushrooms, stems discarded and caps sliced 1/4 inch thick; 1/2 pound oyster mushrooms, sliced 1/2 inch thick; 1 shallot, thinly sliced; 2 garlic cloves, thinly sliced; 1/4 cup dry white wine; 2 tablespoons fresh lemon juice; 1 teaspoon finely chopped thyme; 1 tablespoon finely chopped parsley, plus more for garnish; Kosher salt; Freshly ground pepper; Four 1/2-inch-thick slices of rustic sourdough bread; 1/2 pound fresh ricotta cheese (1 cup); 1/4 cup tarragon leaves; 1/4 cup snipped chives