Precook sliced potatoes in microwave to soften; otherwise they don’t cook all the way through.
Layer sliced potatoes, meat, and veggies (we like spinach). Top with white sauce.
Bake at 350 °F for 45-60 minutes. Since all the ingredients are already cooked, you are basically only heating it through.
My husband’s favorite was potato, hamburger, spinach. Kids liked potato, ham.
I imagine you could also use this with safe pasta. If you had a safe “cheese” sub, you could grate some on top.
Here is my GFCF White Sauce.