1. In a large frying pan, heat 2 tablespoons of the oil with the butter over moderately high heat. Add the mushrooms, the minced garlic, the salt, 1/8 teaspoon pepper, and the sage. Cook, stirring occasionally, until the mushrooms are golden, 5 to 10 minutes. Stir in the chopped parsley. Remove from the heat.
2. In a blender or food processor, put the olives, parsley leaves, smashed garlic, anchovy paste, the remaining 6 tablespoons olive oil, the lemon juice, and 1/4 teaspoon pepper. Blend or process to a coarse puree.
3. Spread the mushroom mixture on eight of the bruschetta, and the tapenade on the rest.