Vegan Cauliflower-Cashew Crostini With Tapenade

For the cauli-cashew cream:
1 cup steamed cauliflower florets
½ cup raw cashews, soaked overnight
2 tablespoons water
1-½ tablespoons nutritional yeast
1 teaspoon fresh lemon juice
1 teaspoon Dijon mustard
½ teaspoon garlic powder
½ teaspoon onion powder
⅛ teaspoon white pepper
⅛ teaspoon salt

For the portabello tapenade:
1 cup pitted Kalamata olives
⅓ cup chopped portabello mushrooms
1 garlic clove
2 teaspoons capers
1 teaspoon fresh lemon juice
⅛ teaspoon freshly ground black pepper

For the crostini:
1 narrow baguette, cut into 16 ⅜-inch thick slices
3 tablespoons chiffonade-cut fresh basil, for garnish
Balsamic vinegar for serving (optional)