Makes 6.
From “R.S.V.P.,” Bon Appétit, March 2008.
- 2 garlic cloves, unpeeled
- Olive oil (for drizzling)
- 1 cup mayonnaise
- 1/3 cup minced fresh basil leaves
- 1 teaspoon plus 3 tablespoons balsamic vinegar
- 6 tablespoons butter, divided
- 1 pound portobello mushrooms (about 5 large), stems trimmed, cut into 1/4-inch-thick slices
- 1 1-pound loaf rustic Italian bread (such as ciabatta or focaccia), halved horizontally
- 1/3 cup freshly grated Parmesan cheese
- 1 large tomato, thinly sliced
Preheat oven to 400°F. Place garlic in small ovenproof dish. Drizzle with olive oil and sprinkle with salt and pepper. Cover tightly with foil and roast until tender, about 30 minutes. Cool; peel and mash garlic. Mix mayonnaise, basil, 1 teaspoon balsamic vinegar, and mashed roasted garlic in small bowl.
Melt 4 tablespoons butter in large skillet over medium-high heat. Add mushrooms and toss to coat. Drizzle remaining 3 tablespoons balsamic vinegar over and cook until tender,stirring often, about 5 minutes. Season with salt and pepper.
Preheat broiler (or use a toaster oven or skillet). Spread remaining 2 tablespoons butter over cut sides of bread. Broil bread, buttered side up, until golden brown, about 2 minutes, watching closely to prevent burning. Spread desired amount of garlic–basil mayonnaise over toasted sides of bread. Arrange mushrooms in even layer over bottom half of bread. Sprinkle Parmesan cheese over. Arrange tomato slices in single layer over cheese. Cover with top half of bread, cut into 6 sandwiches, and serve.