Preheat the oven to 190C (375F).
Heat some olive oil in a large non-stick skillet over a medium-high heat.
When hot, place the meat onto the skillet and cook for 3-4 minutes without touching it to achieve a golden-brown crust. Then, flip and cook for 3-4 minutes again. Season with salt and pepper and break into small pieces using a spatula. Keep cooking for 5-10 minutes, stirring occasionally until fully cooked and liquids have evaporated. At the end, taste and adjust seasoning if needed. Remove into a large bowl.
To the same skillet, add the butter. When melted, add the carrots, onions, and garlic and cook until just softened. Then add the wine and cook until reduced by half. Add the tomato purée, Worchester sauce, chicken stock, rosemary, and thyme, then mix well. Cook, stirring occasionally, until the liquids are reduced by half.
Add the cooked meat and frozen peas. Cook for 5-7 minutes or until bubbly and the peas are hot, but still bright green. Remove from the heat.
Add the meat and veggie mixture to the casserole dish (around 8”x11” or 20cm x 28cm) and spread evenly, pressing in. Spread the mashed cauliflower on top and sprinkle ½ cup of parmesan cheese. Bake for 18-20 min or until the cheese has melted and is golden brown.
Let the dish rest for 20 minutes before cutting in and serving with freshly chopped chives.