In a large skillet over medium high heat, bring butter and cooking oil to a sizzle. Cook onions and bell peppers until softened and lightly caramelized.
In a large bowl mix together ground beef, bread crumbs, eggs, garlic powder, worcestershire sauce and salt & pepper.
Preheat oven to 350 degrees. Place parchment paper on a baking sheet and place half of the meat mixture into the center of parchment paper and form an oval shape about 1 inch thick. Press center of the meat mixture into a bowl shape. Place 3 slices of cheese into center of bowl. Place all cooked onions and peppers on top of cheese. Cover with additional 3 slices of cheese. Take remaining meat mixture and cover the top layer of cheese. Make sure to seal the top meat mixture to the bottom meat mixture to keep filling and cheese in.
Bake for 45 minutes to an hour until meat loaf is done and temperature of the meatloaf is 165 degrees. Pull meatloaf out of oven and place remaining cheese slices on top. Place back in oven for 15 minutes to lightly brown and melt the cheese. Let sit for 5 minutes before serving.
