Put the potatoes in a saucepan, cover with salted water, and simmer for 15 to 18 minutes, until just tender at the center. Drain, cool slightly, and slice 1/4 inch thick.
Heat the oven to 400°F (200°C) and lightly butter a 2-quart baking dish.
Cook the Filling:
Cook the bacon in a skillet over medium heat until lightly browned. Add onions and cook for 10 minutes until soft.
Add garlic for 30 seconds, then pour in wine and simmer until reduced by half. Stir in cream, pepper, and salt.
Assemble and Bake:
Layer half the potatoes in the dish, add half the bacon mixture, and repeat. Place the cheese over the top, rind side up if using halved rounds.
Bake for 25 to 30 minutes, until the cheese is melted and browned in patches. Rest 10 minutes before serving.
Notes
If Reblochon is unavailable, use a mild washed-rind cheese that melts smoothly.
Season cautiously because bacon and cheese already contribute plenty of salt.