In a large saucepan, melt the butter. Once melted, add the gluten-free flour. Whisk the butter and flour together until combined.
Add ½ cup chicken broth and whisk until combined. Add another ½ cup chicken broth and whisk again. Finally, add the last ¼ cup of chicken broth and whisk until smooth. Add more broth if the sauce is not yet smooth.
Sprinkle in the salt and pepper. Add milk and 1 cup of shredded cheese. Whisk until cheese is melted. Add green onion tops, stir the sauce, and set aside.
Wash potatoes and peel them if you would like to.
Thinly slice the potatoes on a cutting board with a mandoline or a sharp knife, cutting them as evenly as possible.
If your ham is not diced, do that now.
In a greased 9x13-inch baking pan, layer the sliced potatoes.
Next, add the diced ham.
Pour the cheese sauce evenly over the potatoes. Top with the remaining 1 cup of shredded cheese.
Cover the pan and bake for 45-55 minutes in a 350 degrees F oven. Uncover the potatoes and bake for another 15-25 minutes or until fork-tender. Garnish with green onion tops.
Serve immediately.
Store leftovers in an airtight container in the refrigerator and enjoy within four days.
Notes
Note 1: The recipe was tested with Bob’s Red Mill 1-to-1 gluten free flour in the light blue bag. Note 2: Milk options include whole, 1% or 2%, do not use skim milk. It is too thin to create a creamy sauce. If lactose free is needed, use it. Unsweetened almond milk will also work. Note 3: Russet potatoes can be used but must be peeled because the skin thicker. Low FODMAP Notes:Low FODMAP ingredient information is based on the Monash University Food App and FODMAP Friendly App testing results.