Preheat oven to 360 degrees F (180 degrees C).
Firstly we're going to mash the potatoes. Peel, chop and boil Potato (750 gram) until tender and put in a large pot with Butter (1 tablespoon), Milk (2 tablespoon), Salt and Pepper (to taste). Mash it together.
Add Olive Oil (to taste) to a pan on medium heat. Then add Yellow Onion (1), Garlic (2 clove), Carrot (2), and Zucchini (2). When the veggies start to soften, add the Lean Ground Beef (500 gram). Using a wooden spoon, break up meat and allow to brown.
Next add Tomato Paste (2 tablespoon), Worcestershire Sauce (2 tablespoon), Water (1/2 cup), and Salt and Pepper (to taste). Stir and allow to simmer for 5-10 minutes.
Split the meat mixture between six ramekins and top each with mashed potatoes. Use a fork to score each of the mashed potato tops. Cook in the preheated oven for 20 minutes or until golden on top.