Open-Face Brie, Apple, and Arugula Sandwiches
- Kosher salt and freshly ground black pepper
- 1 medium Fuji apple, cored and thinly sliced
- 8 tsp. Dijon mustard
- 8 oz. Brie, thinly sliced
- 8 slices rustic artisan bread (about 2-½ by 6 inches and ¾ inch thick)
- 4 cups packed baby arugula
Position a rack 6 inches from the broiler and heat the broiler to high. Put the bread slices on a rimmed baking sheet and set under the broiler. Broil until nicely toasted, 1 to 2 minutes. Remove the pan from the oven, flip the bread over, and spread 1 tsp. of the mustard evenly on each untoast...