1) Preheat the oven to 200 degrees C/Gas Mark 6. Arrange the bacon slices on a sheet tray. Put in the oven and bake until crisp, about 8 to 10 minutes. Remove the bacon from the pan to a cutting board and chop. Set aside.
2) In a large bowl, mix together the beef, Worcestershire, onion soup mix, bread crumbs, black pepper, stock and the chopped bacon. Form portions of the meat around bocconcini to make smooth balls. Arrange the meatballs on a sheet pan with a rack and bake until thoroughly browned, about 10 to 15 minutes.
For the marinara:
1) Add the oil to a medium saucepan over medium-high heat. When the oil is hot add the onion, garlic, basil, oregano and pepper and saute for a few minutes. Stir in the crushed and diced tomatoes, red pepper flakes and the bouillon. Lower the heat and simmer for 10 to 15 minutes.
2) Remove the meatballs from the pan to a serving platter and serve with the marinara sauce.