Preheat oven to 375°F.

Grease a 9×13-inch baking dish generously with butter.

Use a mandolin to slice potatoes evenly (¼-inch or slightly thinner).

If you don’t have a mandolin:

Just make sure your slices are even and uniform—about ⅛–¼ inch thick. They don’t have to be perfect, but even thickness ensures the potatoes cook evenly.

In a medium saucepan, combine chicken stock + heavy cream.

Bring the mixture up to a gentle boil while watching it carefully.

Once bubbling, reduce heat to a low simmer.

Add the fresh rosemary sprigs.

Let the sauce simmer 10–12 minutes, keeping it at a low, steady bubble.

After 10–12 minutes, turn the heat to low (or completely off) and stir in:

8 oz Boursin

½ cup grated Parmesan

Stir gently until smooth.

Season with salt & pepper. Remove rosemary sprigs before pouring.

Note: If some sauce reduces too much or thickens heavily, just splash in an extra bit of heavy cream—totally fine.

Add all sliced potatoes to the baking dish in a rustic, loosely stacked pattern.

This gives the dish that beautiful old-school scalloped look—see photos!

Season the potatoes generously with salt + pepper.

Sprinkle ½ cup grated Parmesan over the potatoes, pushing some cheese gently down between the layers.

Scatter fresh thyme leaves all over the potatoes.

Pour the warm cream sauce evenly over the entire dish.

Shake the dish slightly so the sauce settles between all the potatoes.

Sprinkle 8 oz shredded mozzarella over the top.

Add a few more thyme leaves for extra flavor.

Spray the underside of your foil with nonstick spray (a MUST so cheese doesn’t stick!).

Let stand 5–10 minutes before serving—this helps the sauce settle.

Add fresh chives, thyme, or a little more Parmesan if desired.

Serve warm and enjoy pure holiday comfort.