Heat the oven to 180 °C. Lay the freshly sliced bread, not too close together, on a baking tray greased with olive oil, and put it into the oven. When the slices are golden brown on one side, turn them over so the colour becomes the same all over. Use a fork to combine the gorgonzola and milk, until you obtain a thick creamy mixture. Chop the walnuts, put 1 or 2 spoonfuls (the larger pieces) on one side to garnish the crostini, and add the rest to the cream you've made. When the bread is golden brown, remove it from the oven and, while still warm, spread the gorgonzola and walnut mixture on it. Garnish the crostini with a few pieces of walnut in the centre of each one.