Place the whole milk in a saucepan over medium heat and let it boil.
Using a fork, remove the cream that forms on top and save it in a container. You will repeat this process until no more cream forms. This step will take about an hour.
Mix the sugar and one cup of the remaining boiled milk in a pot until a syrup consistency has formed.
Beat the yolks until they are pale and add them to the mixture of sugar and milk. Stir until it is well-incorporated.
Add the raisins and the cream we first separated from boiling the milk and mix it carefully. Let it simmer for about 10 minutes without stirring.
Transfer your pudding to individual servings and let them cool in the refrigerator until they have thickened.