Even my husband likes this flavorful mushroom sandwich.
Preheat oven to 400 degrees F (200 degrees C).
Place mushroom slices in a bowl. Sprinkle mushrooms with red wine vinegar. Lay the bread slices on a baking sheet. Spread mustard evenly on one slice. Arrange the mushroom slices on the slice of bread with the mustard. Place the green olive slices on the other slice of bread. Cover each piece of bread with the Havarti cheese.
Bake in preheated oven until the cheese melts, 5 to 7 minutes. Remove from oven and put the slices together to make a sandwich.
Per Serving: 467 calories; protein 20.7g; carbohydrates 40.5g; fat 26.1g; cholesterol 71mg; sodium 1587.2mg.