Cost information for the following is not included. Normally this is because the quantity or ingredient is unknown
For the mustard filling:
Salt to taste (if using unsalted butter)
Or
For the Anchovy filling:
A Few Anchovies (start with 2-3 and adding more only after you taste it as they are really salty)
For the Olive & Chilli filling:
Paprika to taste
Chilli to taste (each chilli is different so add only a bit before tasting it first).
NOTE:
You can divide the cooked yolks and make different fillings.
Suggestions?