Preheat your oven to 400°F (200°C).
Place the cubed yellow potato and cauliflower florets in a pot of boiling water and cook for 12-15 minutes until very soft.
While the vegetables boil, heat a large oven-safe skillet over medium-high heat and add the ground beef, diced onion, and diced carrots.
Cook the beef mixture for 8-10 minutes, breaking it apart with a wooden spoon, until the meat is browned and the vegetables are beginning to soften.
Stir in the tomato paste, dried thyme, sea salt, and black pepper, cooking for 1 minute until fragrant.
Pour in the beef broth and add the frozen peas, then reduce heat to low and simmer for 3-5 minutes until the liquid has slightly thickened into a gravy.
Drain the cooked potato and cauliflower, then return them to the pot and mash thoroughly with the ghee and a pinch of salt until smooth and creamy.
Spread the mash evenly over the beef mixture in the skillet, using a fork to create decorative peaks on the surface.
Place the skillet in the oven and bake for 15-20 minutes, or until the topping is lightly golden and the edges are bubbling.