Soak the salt cod in a large quantity of cold water for 1 to 2 days in refrigerator. Change water frequently, be sure fish is kept submerged.
Drain and place in large covered pot or saucepan. Pour in enough cold water to cover and boil over high heat. Reduce to medium heat, cover and simmer until tender about 10 – 15 minutes. Drain and cool. Flake with a fork.
Heat olive oil and milk over low heat in separate saucepans.
Place cod in food processor and gradually pour in olive oil and milk, alternating with small amounts of each. Puree until smooth. Season with lemon juice and pepper to taste.
Preheat oven to 350º F. Rub bottom and sides of 2 quart baking dish with crushed garlic.
Pour in pureed mixture and bake uncovered about 10 minutes, until lightly browned on top and heated through.