Start by preheating the oven to 425 degrees F. Place a large sheet of regular foil on a large (13 x 18-inch) sheet pan. Spray both the sheet pan and the foil generously with nonstick cooking spray.
Place the peeled and chopped (into small pieces) potatoes along with a generous pinch of salt and pepper in the center of the foil.
Fold the foil up around the potatoes and add in the water. Seal the potatoes into a packet. Do NOT use heavy duty foil or more than one piece of foil or the potatoes won't cook properly.
Place in the oven for 10 minutes. Meanwhile, prepare the mini meatloaves.
In a large bowl, add in the egg and lightly beat it with a fork. Using a cheese grater, grate the onion (grating keeps you from getting a bite of raw onion - yay!) and add it to the bowl along with the Italian seasoning, tomato paste, Panko, Worcestershire sauce, milk, 1 teaspoon salt, 1/2 teaspoon pepper, and chopped parsley. Whisk ingredients together and then add in the ground beef.
Mix the ingredients together being careful not to over-mix or mash the meat as that creates a denser meatloaf. Handling as little as possible, form 6 small meatloaves. Add to the tray with the potatoes and spread the ketchup evenly among the top of the meatloaves.
Place in the oven for 20-25 minutes. Remove from the oven, dab up some of the grease (shouldn't be too much with lean ground beef) with a napkin, and add the trimmed green beans in the last section of the sheet pan. Drizzle with olive oil and about 1/2 teaspoon salt and 1/4 teaspoon pepper. Toss and place in the oven for another 15-20 minutes or until the beans are roasted and the meatloaf is cooked to an internal temperature of 160 degrees F.
Remove from the oven, and carefully open the foil pack of potatoes. Transfer the potatoes to a large mixing bowl and add in the butter, milk, and salt + pepper to taste. Use a potato masher to mash the potatoes and if needed, hand mixers to make them smooth.
If desired, prepare the gravy packet according to package directions to serve with the potatoes.