Boil the potatoes in a pan of water. When cooled, crush the potatoes, you can leave the skin on if you want.
Fry the bacon until crisp, remove and drain on some kitchen paper.
Add the butter to the same pan and fry the finely sliced onions until translucent.
Tartiflette recipes usually ask for generous layers of potatoes. As we are here making two small portions in Ramekins, layer the potatoes thinner in order to get a few layers into the Ramekins. First, add a layer of crushed potatoes. Next, add a thin layer of the bacon and onion mixture and top this with thinly sliced Reblochon cheese. Sprinkle with a little white wine and pour over some cream.
Add more layers to fill your Ramekin, ending up with a top layer of potatoes smothered in some cream (I ended up with just 2 layers, topped with potatoes & cream)
Cook the tartiflettes in a pre-heated oven (170°C/fan150°C/gas 3) for approx. 40 minutes.