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Open-Faced Roast Beef Sandwich Casserole - layers of toasty bread, tender roast beef & creamy, buttery mashed potatoes create this delicious casserole. Simply Sated
4.34 from 6 votes

Open-Faced Roast Beef Sandwich Casserole

Layers of toasty bread, tender roast beef & creamy, buttery mashed potatoes come together to create this delicious casserole. The recipe for the beef makes enough to make 1 casserole with extra beef to use in other dishes. If desired, double the other ingredients to make 2 casseroles.
Course Entree, Main
Prep Time 40 minutes
Cook Time 6 hours
Total Time 6 hours 40 minutes
Servings 4 -6
Author Susie Gall


  • For the Beef:
  • 2 packages .6 to 1 ounce each dry Au Jus flavored Gravy Mix
  • 2 packages .7 ounce each Good Seasons Italian Salad Dressing Mix
  • 1 box 32 oz. Beef Stock
  • 5 pounds beef roast Bottom Roast works well
  • water if needed
  • ---------------------------
  • Other:
  • 1.5 pounds Yukon Gold Potatoes peeled, steamed & mashed.
  • 1/4 cup butter
  • 1 Baguette or similar-type bread sliced & toasted on both sides (no need to butter the slices)
  • ½ cup grated or shredded cheese – Gruyere Parmesan, Swiss or Cheddar work well. (optional)
  • Fresh Parsley or favorite herb for garnish - optional


  1. Spray crock-pot with cooking spray and place beef inside.
  2. Sprinkle the Au Jus and Italian Dressing Mixes over the roast.
  3. Pour beef broth on top and add extra water to cover the roast.
  4. Cook 4-5 hours on HIGH or 6-8 hours on LOW.
  5. After beef has cooked, strain the broth through a metal sieve and into a bowl.
  6. If thin slices of beef are needed, let beef cool before slicing – if possible, place in an airtight container and refrigerate overnight for ease in cutting thin slices.
  7. -----------------------
  8. For the Toast:
  9. Preheat oven to 375F.
  10. Slice baguette or bread into 1" thick slices and place the slices on a baking sheet.
  11. Toast slices 5-7 minutes per side or until golden on both sides.
  12. Remove from the oven and set aside until time to assemble the casserole.
  13. -----------------------
  14. For the Mashed Potatoes:
  15. Peel and cube potatoes and place them in a steamer basket.
  16. Steam cubed potatoes until fork tender approximately 15-20 minutes.
  17. Press potato cubes through a ricer into a bowl. Use a potato masher if a ricer isn't available.
  18. Add butter to the mashed potatoes and season with salt & pepper.
  19. Mix butter and potatoes until the butter in incorporated.
  20. Taste & adjust the amount of butter adding enough butter to make the potatoes creamy.
  21. Variation: http://www.simplysated.com/sweet-gold-mashed-potatoes/
  22. ----------------------------
  23. To Assemble:
  24. Spray a deep-dish pie plate or casserole dish with cooking spray.
  25. Place the toasted bread in an even layer in the bottom of the casserole dish.
  26. Layer beef slices over the bread.
  27. Pipe or spoon mashed potatoes over the beef.
  28. Pour 1 cup au jus over the mashed potatoes.
  29. Bake at 375F 20-30 minutes or until the top is golden (or has some color). If desired or needed, turn the oven to broil to get more color on the casserole. Watch closely so the casserole doesn't burn.
  30. Remove from the oven and let set 5 minutes before serving.
  31. If desired, sprinkle some shredded beef, cheese & herbs on top.
  32. After placing a serving of casserole on each plate, pour desired amount of extra Au Jus over each serving.
  33. Enjoy!

Recipe Notes

This beef makes the BEST Beef Au Jus sandwiches (http://www.thecookierookie.com/french-dip/), Regular Open-Faced Roast Beef Sandwiches or piled high with au jus over baked potatoes.