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Philly Cheesesteak Grilled Cheese Casserole
Get ready to experience the ultimate comfort food mashup with this Philly Cheesesteak Grilled Cheese Casserole! This crowd-pleasing dish combines all the savory goodness of a classic Philly cheesesteak with the gooey satisfaction of grilled cheese, transformed into a hearty, sharable casserole format.
Perfect for busy weeknights or weekend gatherings, this casserole delivers bold flavors and melty cheese in every bite. It’s the kind of meal that brings everyone to the table with excitement and leaves them asking for the recipe before they’ve even finished their first serving.
Why You’ll Love This
- Combines two beloved comfort foods into one irresistible dish
- Ready in just 45 minutes from start to finish
- Perfect make-ahead option that reheats beautifully
- Customizable with your favorite cheeses and add-ins
- Kid-friendly while still sophisticated enough for adults
Ingredients
- 9 oz thinly sliced roast beef
- 1 cup yellow onion, diced
- 1 cup green bell pepper, diced
- 0.87 oz brown gravy mix packet
- 1/2 cup water
- 12 slices white or whole wheat bread
- 1/2 cup margarine or butter, softened
- 4 cups shredded mozzarella cheese
Instructions
- Preheat your oven to 400°F and grease a 9×13 inch baking dish. Chop the roast beef slices into bite-sized pieces – this makes it easier to eat and distributes the flavor better throughout the casserole.
- Heat a large skillet over medium-high heat with a dab of butter or margarine. Add the chopped roast beef, diced onions, and green peppers. Cook everything together, stirring frequently, until the onions become translucent and the peppers start to soften – about 5-7 minutes.
- Sprinkle the brown gravy mix over the beef and vegetables, then add the water. Stir everything together until the gravy coats all the ingredients evenly. This creates that rich, savory base that ties all the flavors together. Remove from heat and set aside.
- Spread 1/4 cup of margarine on 6 slices of bread, then cut each slice in half. Place these pieces margarine-side down in a single layer in your greased baking dish. Sprinkle 2 cups of mozzarella cheese over the bread layer.
- Spoon the roast beef mixture evenly over the cheese layer, spreading it out to cover the bread completely. Top with the remaining 2 cups of mozzarella cheese – this creates those amazing gooey, stretchy layers.
- Spread margarine on the remaining 6 slices of bread and cut them in half. Place these pieces margarine-side up on top of the casserole in a single layer. Bake for 26-30 minutes until the top bread is golden brown and the cheese is bubbly.
- Let the casserole rest for about 5 minutes before slicing – this helps it hold together better. Cut into squares and serve immediately while the cheese is still melted and gooey. This is comfort food at its finest!
Tips & Variations
- For extra flavor, add a tablespoon of cream cheese to the steak mixture
- Try pepper jack cheese for a spicy kick or Swiss for a milder flavor
- Substitute thinly sliced chicken for the steak to make a chicken Philly version
- Add a sprinkle of Italian herbs or hot pepper flakes for extra seasoning
- For a shortcut, use pre-sliced frozen peppers and onions
- Make it ahead and refrigerate, then bake for an extra 10 minutes when ready to serve
Serving Suggestions
This hearty casserole pairs wonderfully with a simple green salad dressed with vinaigrette to cut through the richness. For a true diner experience, serve with a side of crispy potato chips or a small bowl of dill pickle spears.
If you’re feeding a crowd, consider setting up a topping bar with hot sauce, extra cheese sauce, or sautéed jalapeños so everyone can customize their portion.
Notes
- Leftovers will keep in the refrigerator for up to 3 days in an airtight container
- For best results when reheating, use an oven or toaster oven rather than a microwave to maintain the crispy texture
- The casserole is done when the bread is golden brown and the cheese is completely melted and bubbly
FAQs
Can I use different bread?
Absolutely! Texas toast, French bread, or even regular sandwich bread will work, though sourdough provides the best flavor and structure.
How do I know if my steak is sliced thin enough?
The steak should be almost paper-thin. If you’re having trouble slicing it yourself, ask your butcher to slice it for cheesesteaks or partially freeze the meat for 20 minutes to make it easier to slice thinly at home.
Can I make this vegetarian?
Yes! Substitute the steak with extra mushrooms, or add plant-based meat alternatives designed for beef substitution.
Can I freeze this casserole?
You can freeze it before baking. Assemble completely, cover tightly, and freeze for up to 1 month. Thaw overnight in the refrigerator before baking, adding 10-15 minutes to the baking time.
Servings8
Prep15 min
Cook30 min
Calories465 kcal
Ingredients
- 9 oz thinly sliced roast beef
- 1 cup yellow onion, diced
- 1 cup green bell pepper, diced
- 0.87 oz brown gravy mix packet
- 1/2 cup water
- 12 slices white or whole wheat bread
- 1/2 cup margarine or butter, softened
- 4 cups shredded mozzarella cheese
Steps
- Preheat your oven to 400°F and grease a 9x13 inch baking dish. Chop the roast beef slices into bite-sized pieces - this makes it easier to eat and distributes the flavor better throughout the casserole.
- Heat a large skillet over medium-high heat with a dab of butter or margarine. Add the chopped roast beef, diced onions, and green peppers. Cook everything together, stirring frequently, until the onions become translucent and the peppers start to soften - about 5-7 minutes.
- Sprinkle the brown gravy mix over the beef and vegetables, then add the water. Stir everything together until the gravy coats all the ingredients evenly. This creates that rich, savory base that ties all the flavors together. Remove from heat and set aside.
- Spread 1/4 cup of margarine on 6 slices of bread, then cut each slice in half. Place these pieces margarine-side down in a single layer in your greased baking dish. Sprinkle 2 cups of mozzarella cheese over the bread layer.
- Spoon the roast beef mixture evenly over the cheese layer, spreading it out to cover the bread completely. Top with the remaining 2 cups of mozzarella cheese - this creates those amazing gooey, stretchy layers.
- Spread margarine on the remaining 6 slices of bread and cut them in half. Place these pieces margarine-side up on top of the casserole in a single layer. Bake for 26-30 minutes until the top bread is golden brown and the cheese is bubbly.
- Let the casserole rest for about 5 minutes before slicing - this helps it hold together better. Cut into squares and serve immediately while the cheese is still melted and gooey. This is comfort food at its finest!
Nutrition (per serving)
- Calories: 465 kcal
