Cheesy Ground Beef Sandwiches

In a large skillet over medium-high heat, sauté the diced onion and mushrooms until they begin to soften.

Season with salt and pepper, then add the diced red bell pepper and continue to cook for a few more minutes.

Stir in the minced garlic and cook until fragrant, about 30-60 seconds.

Remove the cooked vegetables from the skillet and set aside in a bowl.

In the same skillet, add the ground beef and cook, breaking it apart, until fully browned. Drain any excess grease.

Stir in the tomato paste, ketchup, yellow mustard, Worcestershire sauce, sugar, garlic powder, and red pepper flakes.

Return the cooked vegetables to the skillet with the beef mixture and stir to combine. Let it simmer for a few minutes.

Toast the brioche buns and place them on a foil-lined baking sheet.

Place a slice of provolone cheese on each bottom bun, then top generously with the ground beef mixture.

Place another slice of provolone cheese on top of the meat.

Place the baking sheet under the broiler for 1-2 minutes, or until the cheese is melted and bubbly.

Place the top buns on the sandwiches and serve immediately.