Brown the Beef:

• Heat a cast iron skillet over medium-high heat.
• Add ground beef and cook, breaking it apart, until browned (about 4-5 minutes).
• Drain excess fat, leaving about 1 tablespoon for flavor.

Sauté the Vegetables:

• Push the beef to one side of the skillet. Add butter to the other side.
• Stir in mushrooms and onions, cooking for 3-4 minutes until softened.
• Sprinkle Montreal steak seasoning over the mixture and stir well.

Create the Sauce:

• Sprinkle flour over the beef and vegetable mixture, stirring to coat.
• Slowly pour in chicken broth while stirring to avoid lumps.
• Add steak sauce and Dijon mustard, mixing until fully incorporated.

Simmer and Thicken:

• Reduce heat to medium and let the mixture simmer for 5-7 minutes until the sauce thickens.
• Stir occasionally to prevent sticking and ensure even cooking.

Assemble the Sloppy Joes:

• Toast burger buns on a dry skillet or under a broiler until golden brown.
• Spoon beef mixture onto the bottom halves of the buns.
• Sprinkle shredded cheddar cheese over the hot filling.
• Top with the other half of the bun and serve immediately.