Begin by cooking the waxy potatoes in salted water with a hint of thyme until just tender, about 15-20 minutes. When they're done, drain and let them cool before slicing them into thin rounds.

Place a skillet over medium heat. Add the chopped bacon or lardons and cook until crispy and golden, about 8-10 minutes.

Toss in the sliced onion with the bacon and cook until softened and translucent, about 5 minutes. If desired, deglaze with dry white wine and allow it to reduce.

Preheat your oven to 200°C (400°F). Prepare your baking dish.

Layer a thin slice of potato at the bottom, followed by bacon and onion. Repeat layering until all potatoes are used, seasoning each layer with salt and pepper.

Cut the Reblochon cheese in half horizontally and place it, rind side up, on top of the layered potatoes.

Pour the heavy cream over the entire dish.

Transfer the baking dish to the oven and bake for 20-25 minutes until bubbly and golden.