In a large bowl, combine the mince, onion, egg, breadcrumbs and herbs. Use your hands to mix until well blended.
Measure out 1/3 cupfuls of the meat mixture and mold around a cube of cheese like a meatball. Shape into a point at one end and lengthen the body a bit by rolling between your hands. Place your ''rat'' into a shallow baking tray and continue with the remaining meat. Insert pieces of uncooked spaghetti into the rounded end of the rats to make tails.
In a medium bowl, stir together the tomato puree, sugar and Worcestershire sauce. Pour over the rats in the dish and cover the dish with a lid or foil.
Bake for 45 minutes in the preheated oven. Uncover the dish and continue to bake for another 20 to 30 minutes, basting occasionally with the sauce to glaze the rats.
While the rats are baking heat the carrots and peas in a small bowl in the microwave for about 15 seconds.
Carefully transfer the rats to a serving plate so that their delicate tails don't fall off. Press peas into the pointy end to make eyes and insert carrot slices to make ears. Spoon some of the tomato sauce around them and serve.