Place a small non-stick frying pan over medium heat; add olive oil, leeks, garlic and butter and cook until the leeks are creamy and soft (approx. 20 mins).
Grate in a pinch of nutmeg and mix in the mustard, set aside to cool.
Spread cream cheese on one slice of bread and add the cooled leeks, then add the cheese slices.
On the other slice spread the fig jam and add it to the top of the sandwich.
Heat a fresh non-stick pan to medium heat.
On the outside of the sandwich add a thick spread of mayo to each side.
Grill both sides until golden and brown.
Add the pickle to the plate and serve immediately for best results.