Preheat oven to 325 F. Generously grease a 2 qt baking dish. Set aside.

Peel potatoes.

Slice them ⅛ inch thick with a mandolin and place the slices in cold water to prevent them from browning while you're working.

Bring a large pot of salted water to a boil.

Place potato slices in water and boil JUST until potatoes are flimsy, yet still very firm (about 2-3 minutes)

Drain potatoes on a kitchen towel and set aside.

Over medium heat, in a large deep skillet, melt the butter.

Add the onions and cook until tender.

Add garlic and cook until fragrant.

Whisk in flour and cook until golden. (about 2 minutes)

Slowly whisk in chicken broth and stir until smooth and creamy.

Slowly whisk in half n half and stir until smooth.

Slowly whisk in heavy whipping cream and stir until smooth.

Continue stirring the mixture and it will begin to thicken. Do not let it boil.

Turn off heat.

Stir in 1 cup of cheese.

Add the salt, black pepper, smoked paprika, dry mustard, and parsley. Taste and adjust the seasonings to your liking.

Gently add the potatoes to the pan and toss so that all of the potatoes are covered in sauce.

Place half of the potatoes into a layer in prepared dish.

Top with half of the remaining cheese.

Top with the remaining potatoes and sprinkle on the rest of the cheese.

Cover tightly with foil paper.

Bake on middle rack for 30-40 minutes.

Remove foil and bake for another 30-40 minutes or until potatoes are tender and cheese is golden.

Remove from oven and let sit for 15 minutes. (I soak up any extra oil on top with a paper towel)

Garnish the top with smoked paprika and fresh chives.

Serve hot!