In a saucepan combine the prunes and water, cover and bring to boil. Simmer for 7-8 minutes until the prunes become soft. Remove from the heat, add the coconut oil and stir well. Puree the mixture. Set aside to cool completely.
Combine the flour and wheatgerm and stir thoroughly. Set aside.
Preheat the oven to 350 F/ 180 C/ gas mark 4. Line a baking sheet with parchment paper. Set aside.
Cream together the butter, peanut butter and sugar until the mixture is pale. Gradually add the egg beating all the time. Pour in the flour mixture bit by bit until it's fully incorporated, without overmixing.
Form small balls (the size of energy balls) and place them on the baking sheet, not too close together. Flatten each ball a little and using your finger or spoon (if you've got a melon baller use that) make little indents in the centre. Fill the centre of each cookie with about 1/2 teaspoon of the prune mixture (if the mixture has become too thick add a few drops of water) and bake for 20 minutes.
Remove from the oven and leave on the baking sheet for 5 minutes. Then transfer onto a cooling rack to cool completely. Yields 18 medium cookies.