The night before, soak the carne seca in cold water in the refrigerator, changing the water 3 or 4 times. The next day, simmer it in fresh water until very tender, about 1 hour (or 30 minutes in a pressure cooker). Drain, cool and shred, discarding any gristle.
Melt 2 tablespoons of butter in a skillet over medium heat. Cook the onion for 5 minutes, add the garlic and tomato and cook for 5 minutes more. Stir in the shredded beef and herbs and cook for 3 minutes. Taste before adding any salt.
Steam or boil the cauliflower until very soft, about 12 minutes. Drain well, then let it steam dry in the colander for 5 minutes.
Purée the cauliflower in a food processor with the cream cheese, 2 tablespoons of butter and the salt until completely smooth.
Heat the oven to 400°F (200°C). Spread the beef in a 9 by 13-inch baking dish, cover with the cauliflower mash and sprinkle with the mozzarella and Parmesan.
Bake for 20 to 25 minutes, until bubbling and golden. Rest for 10 minutes before serving.