Place the oven rack on the center most position. Preheat oven to 425 degrees F.

In a large dutch oven, melt the butter over medium heat. Add the minced shallot, cooking while stirring, until they are soft and translucent, about 3 - 4 minutes total.

Add the minced garlic and fresh rosemary, continuing to cook for another 30 - 45 seconds, until the garlic is fragrant and no longer raw.

Add the sliced potatoes, chicken broth, cream, salt, pepper, and bay leaves to the shallot mixture. Increase heat to medium high and bring the mixture to a simmer, stirring periodically until simmering.

Once simmering, stir, then reduce the heat to low, cover and continue cooking until the potatoes are almost tender, about 10 - 12 minutes.

Once the potatoes are almost tender, remove the lid, stir, and remove from heat. Discard the bay leaves. Add additional salt and pepper, to taste, if desired.

In a 1 ? quart gratin (or other casserole dish), add ? of the potatoes, then add ? of the parmesan cheese on top. Repeat the layering of cooked potatoes and parmesan in ? increments.

After the last of the potatoes are added, pour any remaining liquid from the dutch oven on top of the potatoes. Top with the remaining parmesan cheese.

Transfer the dish to the preheated oven on the middle rack. Bake at 425 degrees F until the sauce is bubbling and the top is golden brown, 15 - 20 minutes.

Cool on a wire baking rack for 10 - 15 minutes before serving.