Make the mashed cauliflower according to instructions here. Set aside.
Preheat the oven to 400 degrees F (204 degrees C).
Heat oil in a large enameled cast iron skillet over medium heat. Add the onions, carrots, and peppers. Saute for 6-10 minutes, until lightly browned.
Push the vegetables to the sides of the pan. Add the ground lamb, breaking apart with a spatula. Season with salt and pepper. Cook for 7-10 minutes, until the ground meat is brown.
Stir in the broth, coconut aminos, tomato paste, and Italian seasoning. Bring to a boil, then simmer, uncovered, for about 5 minutes, until most of the liquid evaporates and you have meat in a thick sauce. Remove from heat.
Drop dollops of mashed cauliflower over the pan and use a rubber spatula to spread evenly.
Bake for 10-15 minutes, until the edges are bubbly.
If desired, place under the broiler for 2-4 minutes, until the edges are golden.