Heat grill to high and put the bacon lardons on a baking tray. Grill for around 10 mins until crisp, then set aside. Mix the crème fraîche with the nutmeg and caraway seeds (if using) and season.
Working in batches, place a pancake on a non-stick baking sheet, divide the crème fraîche mixture between the 4 pancakes, then top each pancake with the lardons, shallots and cheese.
Put the pancakes under the grill for 2-3 mins (you will need to do this in batches again) or until the cheese is golden and bubbling. While they cook, mix the cucumber with the vinegar and dill, season, then serve alongside the pancakes.