French Dip Sandwich Melt is the perfect mix of juicy, tender roast beef piled high on crusty bread that’s been toasted to golden perfection. What really makes this sandwich shine is the melty cheese layered on top, adding a creamy, gooey touch to every bite. The sandwich comes with a side of rich, savory au jus for dipping, giving it that classic French Dip flavor twist with a melty, toasty spin.
I love making this sandwich when I want something hearty but easy to put together. One of my favorite parts is that you can use leftover roast beef or sliced deli beef, and it still tastes amazing. To make it extra special, I like to add a little caramelized onion or a splash of horseradish sauce before melting the cheese – it just kicks the flavors up a notch!
Serving this French Dip Sandwich Melt with a small bowl of warm au jus makes the meal feel cozy and satisfying. I always think of this sandwich as the perfect comfort food for when I’m craving something warm and filling but don’t want a fuss. Plus, dipping that melty sandwich into the rich broth just can’t be beat—it’s a simple thing that makes every bite feel like a little celebration.
Key Ingredients & Substitutions
Roast Beef: Thinly sliced roast beef is key for tender bites. If you can’t find deli-style, leftover pot roast or brisket works well. For a leaner option, try thin turkey slices, though the flavor will be lighter.
Onions: Caramelized onions add sweetness and depth. Yellow onions work best, but white or sweet onions are good alternatives. Take your time cooking them low and slow for best flavor.
Cheese: Provolone or Swiss melt beautifully and balance the beef’s richness. Mozzarella works too, but it’s milder. For a stronger taste, try Gruyère or fontina.
Bread: A crusty hoagie or French baguette holds up well to dipping. If unavailable, a sturdy ciabatta or sub roll will do. Avoid soft bread that gets soggy quickly.
Au Jus: Beef broth gives the dipping sauce its savory base. Add Worcestershire sauce for extra punch. Low-sodium broth is great if you want to control saltiness.
How Do You Get Soft, Sweet Caramelized Onions Without Burning Them?
Caramelizing onions takes patience but is worth it. Here’s what I do:
- Cook sliced onions in butter over medium-low heat.
- Stir often to prevent sticking or burning, about every 3-5 minutes.
- Cook slowly for 15-20 minutes until onions turn a deep golden brown.
- Add a pinch of salt and dried thyme for flavor during cooking.
- If onions start to dry out, add a splash of water or broth to keep them moist.
Slow cooking draws out natural sweetness and softens texture. Rushing or high heat leads to bitter, burnt onions. It’s easy once you give it time!
Equipment You’ll Need
- Large skillet – perfect for caramelizing onions evenly without burning.
- Small pot – to warm up the beef broth and make au jus for dipping.
- Baking sheet – holds the sandwiches under the broiler to melt the cheese.
- Oven broiler or toaster oven – melts cheese quickly and gives the bread a nice toast.
- Sharp knife – to slice the hoagie rolls or baguette cleanly without crushing them.
Flavor Variations & Add-Ins
- Swap roast beef for thin turkey or chicken for a lighter, milder version.
- Add sautéed mushrooms with the onions for extra earthiness and texture.
- Use pepper jack cheese instead of provolone for a spicy kick.
- Spread a thin layer of horseradish sauce on the bread before assembling for a zesty punch.
How to Make French Dip Sandwich Melt
Ingredients You’ll Need:
Main Ingredients:
- 1 lb thinly sliced roast beef (preferably cooked and leftover or deli-style)
- 1 large onion, thinly sliced
- 2 tablespoons butter
- 1 teaspoon garlic powder
- 1 teaspoon dried thyme
- Salt and pepper to taste
- 4 hoagie rolls or French baguette sections
- 8 slices provolone or Swiss cheese
Au Jus (Dipping Sauce):
- 3 cups beef broth
- 1 tablespoon Worcestershire sauce (optional)
Optional Garnish:
- Fresh parsley, chopped
How Much Time Will You Need?
This recipe takes about 25-30 minutes to prepare, including caramelizing onions and assembling the sandwiches. Broiling and warming au jus add just a few more minutes. It’s a quick meal that’s perfect for lunch or dinner!
Step-by-Step Instructions:
1. Caramelize the Onions:
Start by melting the butter in a large skillet over medium heat. Add the thinly sliced onions and cook, stirring often, until they soften and turn golden brown—this should take about 15-20 minutes. Season with garlic powder, dried thyme, salt, and pepper while cooking. The slow cooking will make the onions sweet and tender.
2. Prepare the Au Jus:
Meanwhile, warm the beef broth in a small pot over low heat. Add Worcestershire sauce if you like, and keep the mixture warm for dipping your sandwiches later.
3. Assemble the Sandwiches:
Preheat your oven’s broiler or a toaster oven. Carefully slice the hoagie rolls or baguettes lengthwise, but don’t cut all the way through. Layer the roast beef inside each roll, then top with the caramelized onions. Place two slices of provolone or Swiss cheese on top of the filling.
4. Melt the Cheese and Toast the Bread:
Place the prepared sandwiches on a baking sheet and put them under the broiler for 2-4 minutes. Watch closely and remove when the cheese is melted and bubbling, and the bread is lightly toasted.
5. Serve and Enjoy:
Remove the sandwiches from the oven and garnish with a sprinkle of fresh parsley, if you like. Serve each sandwich hot with a small bowl of warm au jus on the side for dipping. Enjoy the tasty mix of tender beef, melty cheese, sweet onions, and rich broth!
Can I Use Frozen Roast Beef for This Sandwich?
Yes! Just make sure to fully thaw the roast beef in the refrigerator overnight before using it. Pat it dry with paper towels to avoid excess moisture in the sandwich.
Can I Make the Au Jus Ahead of Time?
Absolutely! You can prepare the au jus up to 2 days in advance and store it in the refrigerator. Reheat gently on the stove before serving to keep it warm and flavorful.
What’s a Good Substitute for Provolone Cheese?
If you don’t have provolone, Swiss cheese is a great alternative. Mozzarella or Gruyère can also work well and melt nicely, just keep in mind the flavor will vary slightly.
How Should I Store Leftover Sandwiches?
Wrap leftovers tightly in foil or plastic wrap and store in the fridge for up to 2 days. Reheat in the oven or toaster oven to keep the bread crispy and the cheese melty again.
