Start the smoker and heat up to 375F. Our personal preference for this recipe is to use oak or pecan; but feel free to experiment with your favorites.

Grease the 9-by-13 inch pan or deep 12-inch cast iron skillet.

In a medium saucepan over moderate heat, melt the butter. Sauté the onion, until translucent, 3 to 5 minutes. Once the onions are soft, add the garlic and cook, stirring, until fragrant, about 30 seconds.

Stir in the flour and cook until it smells toasty, about 1 minute. While whisking constantly, slowly stream in the chicken stock. Then add the milk and half of the thyme. Season with salt and white pepper. Cook over moderate heat, stirring, until the sauce begins to thicken. Remove from the heat.

Layer half of the potatoes in the baking dish. Pour half of the sauce over the potatoes and cover with half of the cheese. Layer the rest of the potatoes on top of the first layer. Pour the rest of the sauce over the top and sprinkle with the rest of the cheese.

Bake in the smoker for 1 hour and 30 minutes, or until you can easily pierce the potatoes with a fork. Let rest for 15 minutes, then sprinkle with the remaining fresh thyme and serve.