Make the pizza base according to the instructions on the packet. Form the dough into 4 balls and roll them out into ovals. Cover lightly with oiled clingfilm and leave in a warm place.
Melt the butter and olive oil in a large frying pan and fry the bacon for 3–4 minutes or until cooked. Add the onions and garlic and fry gently for 5–6 minutes or until soft and golden.
Spread 1 tablespoon of the crème fraîche over each pizza base. Top with slices of potato, some of the bacon and onion mixture and 2–3 slices of Reblochon. Cook in a preheated oven, 220°C (425°F), Gas Mark 7, for 15 minutes until bubbling and golden.
Serve immediately with an extra dollop of the remaining crème fraîche on top, if liked.