Heat 1 tablespoon of the olive oil in a medium saute pan over medium heat and add the peppers, onions and garlic. Saute until just soft, remove to a plate and cool.
When the peppers and onions are cool, combine all of the remaining ingredients together except for the marinara. Pack the meat mixture into an oiled loaf pan, if you do not have a loaf pan, form the meat mixture into a loaf shape on an oiled oven tray or baking dish. Top with the marinara making sure to spread evenly over the top.
Bake for approximately 50 to 60 minutes or until an instant-read thermometer registers 160 degrees F in the middle of the meatloaf. Remove from the oven and let rest for 5 minutes. Slice and serve.