Make a well in the flour, place the egg in the middle and, using a fork, mix together the dough. Continue to knead until you have an even and solid dough. Make a ball from the dough, cover it with cling film and leave to stand for half an hour. In the meantime, grate the Capriccio and Torregio cheese into thin strips, while its nice and cold.
Mix the cheese with the egg and half a teaspoon of kaffir lime zest until you get a soft and even mixture. Roll out the dough using a dough sheeter, making thin strips. Place the strips on the pastry board and use a piping bag to place blobs of the filling along the lower part of the strip, around 4 cm away from each other.
Cover with the upper part of the pastry and seal the edges with your fingertips. Cut out the ravioli shapes using a dough cutter wheel. Cook the ravioli for a few minutes in lightly salted boiling water. Dress with melted traditional butter and white butter.