2 tablespoons butter
1 small yellow onion diced
1 small green bell pepper diced
8 ounces brown mushrooms minced
1/2 teaspoon Kosher salt
1/2 teaspoon fresh ground black pepper
2 pounds lean ground beef 80/20 or 85/15
2 tablespoons ketchup
2 tablespoons Worcestershire sauce
1 cup panko breadcrumbs
8 ounces Provolone Cheese Slices
Preheat the Oven to 375 degrees and Spray a large loaf pan with Cooking Spray. In a large Skillet, add the butter and the Onions and bell peppers, mushrooms, Salt and pepper.
Let brown for 1-2 minutes before Stirring, then let brown for another 1-2 minutes before stirring again.
In a Large bowl add the ground beef, Ketchup, Worcestershire Sauce , eggs , panko Breadcrumbs and the cooled vegetable mixture .
Add half The mixture to your loaf pan then add half of the cheese to the middle of the pan in a 2 inch wide section (I cut the slices into thirds for the right Width).
Cover with the rest of the Meat and form into a rounded top loaf shape. Cook for 40 minutes, then pull out of the Oven, cover with remaining cheese and put back in. Cook for 15-20 minutes , then let rest for 10 minutes before cutting.