Preheat oven to 400°F. Prepare a 9 or 10 inch pie plate with cooking spray.
Heat the butter in a medium saucepan. When the butter has melted, whisk in the flour to create a roux. Continue to whisk until mixture turns a very light brown and has a nutty smell, approximately 4-5 minutes.
Whisk in the half & half, then add the shallots, garlic, rosemary, parsley, thyme, salt, white pepper and 1/2 cup of the shredded Swiss cheese. Remove from the heat and set aside.
Layer the potatoes in a circular fashion. After you complete one layer, cover with just enough half & half mixture to cover it. Repeat layers until the potatoes reach the lip of your pie plate. Pour remaining half & half mixture over potato slices.
Bake, uncovered, for 50-60 minutes or until the potatoes are tender and mixture is bubbly. Remove and cover with remaining 1/2 cup of the Swiss cheese. Return to the oven until cheese has melted, approximately 5-10 minutes.
Remove and allow to set for 5 minutes. Slice and serve.
If you've tried this recipe, come back and let us know how it was in the comments or star ratings.