Skillet-to-Oven Salisbury Steak & Smothered Onion Casserole

🌍 Cuisine: American
🏷️ Category: Main Course
⏱️ Prep: 20 minutes
🍳 Cook: 45 minutes
👥 Serves: 6 servings

📝 About This Recipe

This elevated take on the mid-century classic transforms traditional Salisbury steak into a cozy, family-style bake bubbling with rich umami flavors. We swap the individual patties for a hearty, seasoned ground beef base nestled under a silky, cognac-kissed mushroom gravy and a blanket of golden, melted Swiss cheese. It’s the ultimate comfort food—reimagined with modern techniques to ensure the meat stays juicy and the sauce remains luxuriously glossy.

🥗 Ingredients

The Meat Base

  • 2 pounds Ground Beef (85/15 lean-to-fat ratio for best flavor)
  • 1/2 cup Panko Breadcrumbs (soak in 2 tbsp milk for 5 minutes)
  • 1/2 cup Yellow Onion (grated or very finely minced)
  • 2 tablespoons Worcestershire Sauce
  • 1 large Egg (lightly beaten)
  • 1 teaspoon Garlic Powder
  • to taste Kosher Salt and Black Pepper (be generous with the pepper)

The Mushroom & Onion Gravy

  • 12 ounces Cremini Mushrooms (sliced thick)
  • 1 large Sweet Onion (sliced into thin half-moons)
  • 4 tablespoons Unsalted Butter
  • 1/4 cup All-Purpose Flour
  • 3 cups Beef Bone Broth (high-quality, low sodium)
  • 1 tablespoon Dijon Mustard (adds a necessary tang)
  • 2 tablespoons Cognac or Dry Sherry (optional, for depth)

The Topping

  • 1.5 cups Swiss or Gruyère Cheese (freshly shredded)
  • 2 tablespoons Fresh Parsley (chopped for garnish)

👨‍🍳 Instructions

  1. 1

    Preheat your oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish or a deep oven-safe skillet with butter.

  2. 2

    In a large mixing bowl, combine the ground beef, soaked panko, grated onion, Worcestershire sauce, egg, garlic powder, salt, and pepper. Mix gently with your hands until just combined; do not overwork the meat or it will become tough.

  3. 3

    Form the meat mixture into small, oval-shaped 'mini steaks' (about 12 portions) and place them in a large skillet over medium-high heat. Brown for 3 minutes per side. They don't need to be cooked through, just deeply caramelized. Transfer to the prepared baking dish.

  4. 4

    In the same skillet, melt the butter. Add the sliced onions and mushrooms. Sauté for 8-10 minutes until the onions are translucent and the mushrooms have released their moisture and turned golden brown.

  5. 5

    Sprinkle the flour over the vegetables and stir constantly for 2 minutes to cook out the raw flour taste. The mixture should look like a thick paste coating the vegetables.

  6. 6

    Slowly whisk in the beef broth, a half-cup at a time, ensuring no lumps form. Add the Dijon mustard and Cognac (if using).

  7. 7

    Bring the gravy to a gentle simmer and cook for 5 minutes until thickened enough to coat the back of a spoon. Season with additional salt and pepper to taste.

  8. 8

    Pour the hot mushroom and onion gravy evenly over the beef patties in the baking dish.

  9. 9

    Cover the dish tightly with aluminum foil and bake in the center rack of the oven for 20 minutes.

  10. 10

    Remove the foil, sprinkle the shredded Swiss cheese over the top, and return to the oven for another 10-15 minutes until the cheese is bubbly and starting to brown.

  11. 11

    Let the casserole rest for 5-10 minutes before serving. This allows the gravy to set slightly so it clings to the meat.

  12. 12

    Garnish with fresh parsley and serve warm.

💡 Chef's Tips

For the juiciest results, grate your onion directly into the meat mixture—the juice acts as a natural tenderizer. Don't skip browning the meat; that 'Maillard reaction' provides the deep savory base for the entire casserole. If the gravy feels too thick before baking, add an extra splash of broth; it will thicken further in the oven. You can substitute the Swiss cheese with Sharp White Cheddar or Provolone for a different flavor profile. To make ahead, prepare the meat and gravy, assemble, and refrigerate for up to 24 hours before baking (add 10 minutes to the covered baking time).

🍽️ Serving Suggestions

Serve over a bed of buttery garlic mashed potatoes to soak up the extra gravy. Pair with honey-glazed roasted carrots for a touch of sweetness to balance the savory beef. A crisp green salad with a sharp vinaigrette helps cut through the richness of the dish. A full-bodied Cabernet Sauvignon or a dark stout beer complements the umami flavors perfectly. Warm crusty sourdough bread is essential for cleaning the plate.