Mix the milk, ground beef and pork. Add crumbled feta cheese, raisins, the soaked in milk center of the slice of bread, egg, finely chopped garlic, crushed cloves, cinnamon, a little pepper and salt. Knead well.
Make an incision in the tenderloin, its depth should be 2/3 of the thickness of the fillet. Fill the holes with the mixture. Tie with a string and put the meat in a baking dish. Brush it with olive oil, sprinkle it with salt and pepper and bake for about 90 minutes in a preheated oven, at 356°F (180 °C).
Fry the chopped onion in 2 tablespoons of olive oil until golden brown. Add the sauce released during the baking of the meat, white wine and broth. Boil until the mixture is reduced by half. Cut the meat and pour on the sauce.