Ingredients

• 2 pounds lean ground beef
• 1 red onion, coarsely chopped
• 3/4 cup Italian-seasoned bread crumbs
• 2 eggs
• 1 pinch salt and ground black pepper to taste (optional)
• 1 (8 ounce) package shredded smoked mozzarella cheese
• 1 teaspoon vegetable oil, or as needed
• 4 slices hardwood smoked bacon
• 1 1/2 teaspoons Dijon mustard, divided
• 1 1/2 teaspoons Worcestershire sauce, divided
• 1 red bell pepper, sliced into strips
• 1/2 cup sliced fresh mushrooms
• 1 (8 ounce) package crumbled aged feta cheese

Instructions

1. Preheat oven to 350 degrees F (175 degrees C).
2. Mix ground beef, red onion, bread crumbs, eggs, salt, and pepper together in a large bowl. Divide mixture in half. Press half of the mixture in the bottom of a loaf pan.
3. Run 2 fingers lengthwise down the center of the beef mixture. Fill hollowed space with mozzarella cheese. Mold remaining beef mixture around cheese, pressing down firmly.
4. Heat oil in a large skillet over medium-high heat. Cook bacon slices until lightly browned, about 5 minutes. Arrange bacon slices over beef mixture.
5. Cook and stir 3/4 teaspoon mustard and 3/4 teaspoon Worcestershire sauce in the bacon grease in the skillet for 1 minute. Add bell pepper; cook until softened, 3 to 4 minutes. Spread bell pepper over bacon.
6. Place remaining mustard, Worcestershire sauce, and mushrooms in the skillet; cook and stir until soft, about 5 minutes. Spread evenly over bell pepper. Scatter feta cheese over mushrooms.
7. Cover loaf pan with aluminum foil; place on top of a baking sheet.
8. Bake in the preheated oven until an instant-read thermometer inserted into the beef reads at least 160 degrees F (71 degrees C), 60 to 90 minutes.