Preheat oven to 450°F. Heat Port in small saucepan and simmer until slightly syrupy, about 10 minutes. Cool.
Toss grapes with 1 teaspoon olive oil, balsamic vinegar, pinch of salt, and rosemary sprig. Roast in shallow nonstick baking pan for 12 minutes, until blistered. Cool slightly; drain liquid.
Toss Swiss with flour to coat shreds. In fondue pot or double boiler, simmer white wine for 5 minutes, then whisk in cheese and stir until melted. Add pinch of salt and whisk slowly while simmering additional 5 minutes. Remove from heat.
Heat large skillet over medium heat. Brush both sides of bread slices with remaining olive oil. Grill each slice, both sides, in skillet, turning once. Place 2 slices on serving plates. Top with layer of roasted grapes and arugula. Spoon warm fondue over. Drizzle with Port reduction and top with second slice of bread.
- 1 cup Port
- 2 cups seedless red grapes
- 1/4 cup olive oil, divided
- 1 teaspoon balsamic vinegar
- 1 sprig rosemary
- 1 cup (4 ounces) Wisconsin Swiss cheese, shredded
- 1 tablespoon flour
- 1/2 cup dry white wine, such as Sauvignon Blanc or Pinot Grigio
- 4 slices crusty French bread
- 2 handfuls arugula