Prepare the filling: in a pan heat three tablespoons of oil and brown the minced meat for 10 minutes, add salt and pepper, add the butter and a few tablespoons of tomato sauce and set aside. Prepare the batter for the rags: in a bowl mix the lightly beaten eggs with the flour, water and a pinch of salt, let the batter rest for about an hour.

For the sauce: in a pan heat two tablespoons of oil, add the chopped vegetables and let them soften at medium heat. Add the puree, salt and pepper, cook for about 20 minutes. In a non-stick pan brushed with oil, pour a ladle of batter of the rags and cook the omelet on both sides. Keep doing this until the batter runs out. You should get 4-5 omelets out of it.

Gradually place the rags on the work surface, sprinkle each one with a little grated Grana Padano, a spoonful of meat, a slice of mozzarella and a spoonful of sauce. Wrap them in a cannelloni and line them up in a single layer in a greased baking dish. Pour the tomato sauce over it and sprinkle the remaining grated cheese. Brown in a hot oven at 180 ° for about 10 minutes. Withdraw and serve.