Apple-Gruy&#232re French Toast

Ingredients

• Two 1 3/4-inch-thick slices challah bread from middle of loaf
• 2 ounces grated Gruyère cheese
• 1/4 small red onion, very thinly sliced
• 2 large eggs, lightly beaten
• 3/4 cup whole milk
• 1/4 teaspoon kosher salt
• 1/4 teaspoon ground black pepper
• 2 tablespoons extra virgin olive oil
• 1 small apple, cored, quartered and very thinly sliced

Directions

1. Put one slice of bread on your work surface, the bottom crust nearest you. Cut into bottom crust, parallel to work surface, to make a pocket. Do not cut all the way to top of slice; bread should remain attached there. Gently stuff half the cheese and onion slices in pocket. Repeat with other slice.
2. In a bowl, whisk together the eggs, milk, salt and pepper. Pour custard into a wide, shallow dish. Soak stuffed bread in custard, turning once halfway through, until most of the liquid has been absorbed, about 5 minutes.
3. Heat oil in a large skillet over medium heat. Add half the apple slices in a single layer and cook for 1 minute. Place bread slices in pan, covering apples. Arrange remaining apple slices on top of bread; cook 1 minute more.
4. Reduce heat to medium low (or perhaps low, if you are using a cast-iron skillet or cooking on a powerful burner), cover and cook for 5 minutes. (Since my skillet does not have a cover, I used aluminum foil to make a little lid.) Peek underneath halfway through to make sure the bottom of the bread is not browning too much; if it seems to be, lower the flame or move on to the next step right away, depending on how far gone it is. Uncover and increase heat to medium; cook until bottoms are golden, about 2 minutes. Carefully turn bread and apples and cook until bread is golden and cheese is melted, 3 to 5 minutes.