Slice potatoes to about 1/8” thickness. A food processor or mandolin will make quick work of this. Chop the onion.
Making the Sauce:
In a large sauce pan, melt butter and add onion over medium heat. Saute until onions are softened, about 3-4 minutes. Add garlic and saute for 1-2 more minutes. Add flour and cook stirring well for 1-2 minutes.
Reduce heat to medium low. Combine milk and unsalted chicken broth. Pour in a small amount at a time, whisking to thicken. The mixture will shortly begin to thicken, continue adding a little bit of liquid at a time whisking until thickened and smooth.
After all of the liquid has been added, add in remaining spices, paprika, ground mustard, Mrs. Dash Original no salt blend and pepper. Bring to a boil slightly over medium heat while continuing to whisk and let boil 1 minute.
Casserole Assembly:
Grease or spray an 8" X 8" casserole baking dish. Lay single layer of the potatoes in the bottom. Ladle the cream sauce over the top and lightly spread around to just cover, season with more pepper if desired. Repeat layering with a final topping of cream sauce.
Cover lightly with aluminum foil and bake for 45 minutes.
Remove foil and bake for another 35-45 minutes or until golden brown and potatoes are tender. You may broil for 2-3 minutes to obtain desired golden crispier top.
Allow to rest for 15 minutes on cooling rack to allow the sauce to thicken, before serving.
Notes
If you wish to use some cheese, melt 1 cup shredded Swiss cheese in the sauce. Shredded Swiss should have an average of 85mg per ¼ cup. Adding 1 cup would add 37mg sodium for a total of 63mg per serving.