Pour a little milk, stir with a whisk breaking lumps. Add the rest of the milk in a thin stream, stirring with a whisk. Salt (take into account the salinity of the cheese! I added one small pinch of salt).
Cook over low heat, stirring with a whisk, until the sauce begins to thicken. As soon as the sauce began to thicken, remove from heat.
Add grated cheese and crushed garlic. I pre-warmed garlic in a small amount of oil. Stir.
Return to the heat, stir until the sauce is smooth and the cheese is completely melted. Remove from heat. Sauce is ready.