1. Dilute the dulce with the milk in a saucepan. Heat to a boil.
  2. Separate the egg yolks from the whites in two bowls. Reserve the white for another recipe.
  3. Pour a small amount (about 200 ml) of the boiling liquid over the egg yolks and whip to incorporate the yolks in the liquid.
  4. Pour the rest of the liquid while continuing to whisk for a homogeneous mixture.
  5. Put the liquid back in the pan and cook the mixture up to 82C by continuously stirring the appliance with a spatula so that it does not stick to the pan.
  6. Cut the heat of the mixture as soon as the temperature is reached, by transferring it to a bowl.
  7. Cool in the fridge by mixing the appliance every 10 minutes until it is at the temperature of your fridge. Keep refrigerated until use.