In a large Dutch oven or crockpot, heat the olive oil on medium-high. Add the beef and fry for 5 minutes to brown, remove from pan.
reduce heat to low-medium and add the onions and carrots then sauté for 15 minutes to soften. Increase the heat to medium and add the tomato paste, garlic, thyme, rosemary and flour then cook for 2 minutes, stirring constantly.
add the stock and Worcestershire and deglaze the pan. Return the beef to the pan and simmer for 40 minutes. Season generously.
while the beef is simmering, add the potatoes to a saucepan of lightly salted cold water and bring to a boil. Simmer for 15 minutes or until tender. Preheat oven to 220°C.
Drain the potatoes then mash with the butter and 2/3 of the pecorino.
assemble the pie in a casserole dish by placing the beef mixture in the bottom then topping with the mash. Sprinkle over remaining pecorino. Bake in prepared oven for 25 minutes or until golden and crispy.