French Onion Beef Cheddar Potato Gratin Step-by-step instructions

Before you start

Before beginning, ensure all ingredients are measured and ready. Peel and thinly slice the potatoes, keeping them in a bowl of cold water to prevent browning until they are ready to be layered. Finely slice the onions to ensure they caramelize evenly.

Preheat the oven to 375°F (190°C) so it is fully heated by the time the assembly is complete. Have the aluminum foil ready to cover the dish, and ensure the baking dish is clean and dry before you start layering the potatoes and beef mixture.

Instructions

Preparing the filling

1. 1Prepare the beef and onions
   Heat a large skillet over medium-high heat. Add the ground beef and cook until browned, breaking it apart with a spoon. Remove the beef and set aside. In the same skillet, sauté the sliced onions until soft and caramelized, about 10 minutes. Return the beef to the skillet and stir to combine.
   Look for The onions should be golden brown and the beef fully cooked through.
   Safe temperature 160°F (71°C) internal temperature (ground meat)
   Tip Caramelizing the onions slowly ensures deep flavor.

The ground beef should be fully browned and no longer pink. The onions should be soft, translucent, and golden brown, indicating they have properly caramelized.

The beef and onion mixture should be well combined and fragrant, with the flavors of the beef juices fully integrated. Check that the beef is cooked through to 160°F (71°C) before proceeding to the assembly phase.

Assembling the layers

2. 2Assemble the gratin
   Preheat your oven to 375°F (190°C). In a 9x13 inch baking dish, layer half of the thinly sliced potatoes. Spread the beef and onion mixture evenly over the potato layer. Top with the remaining potato slices. Pour the beef broth over the entire assembly to ensure even cooking.
   Look for Ensure the potatoes are tightly packed for even cooking.
   Tip Use a mandoline for perfectly uniform potato slices.

The potatoes should be arranged in even, overlapping layers to ensure uniform cooking. The beef and onion mixture must be spread in a consistent layer to provide flavor in every bite. When pouring the beef broth, ensure it reaches the edges of the dish. The dish should feel heavy and well-packed, indicating that the layers are properly constructed before the final bake.

Final bake and finish

3. 3Bake and finish
   Cover the baking dish tightly with aluminum foil. Bake for 40 minutes. Remove the foil, sprinkle the shredded cheddar cheese over the top, and continue baking for 15 minutes, or until the cheese is melted, bubbly, and golden brown. Let the dish rest for 10 minutes before serving.
   Look for The cheese should be bubbling and golden brown.
   Tip Resting the dish allows the liquid to redistribute.

The cheese should be completely melted and show a deep, golden-brown crust, especially around the edges of the dish. The dish should be bubbling vigorously, and the steam should be rising from the center. Ensure the potatoes are tender and the entire gratin is heated through. The final rest is essential to ensure the sauce has thickened and the gratin is easy to scoop.

Common mistakes

Avoid slicing the potatoes too thick, as they will not cook through properly within the given time. If the potatoes are too thick, the gratin will remain crunchy rather than tender.

Do not skip the resting period after baking; cutting into the dish immediately will cause the sauce to run and the layers to fall apart. Ensure the dish is covered tightly with foil during the first part of the bake to trap the steam, which is necessary to cook the potatoes thoroughly before the cheese is added.

How to tell it’s done

The gratin is done when the potatoes are fork-tender and the cheese is fully melted and golden brown. Insert a knife into the center of the dish; it should slide through the potatoes with no resistance.

The internal temperature of the beef mixture should reach at least 160°F (71°C) to ensure it is cooked through. Let the gratin rest for at least 10 minutes after removing it from the oven to allow the liquids to settle and the cheese to set slightly for easier serving.

• Ground meat: 160°F (71°C) in the thickest part