Cook potatoes with salt. Peel and Strain. Finally, put butter and mix of fluffy mashed. Onions and garlic sauté in the oil. Put and sliced ​​mushrooms. After 3-4 minutes, is added with some water fuzzy mince. When the mince changes color add grated tomatoes. After 5 minutes, add pepper, parsley and thyme and remove from heat. Half paste is spread in the pan. Then, the minced meat is placed on it and the other half of the puree. Put it in a preheated oven at 220 C for 15-20 minutes. Finally sprinkle with cheese and bake until golden (only top heating element).