Gluten Free Potato-Cauliflower Gratin

This is just a variation on Potato Gratin, of course, inspired by the idea from the low-carb community of substituting cauliflower for potatoes. I love both potatoes and cauliflower, with or without cheese, so this is really the best of both worlds, and definitely lower in carbs than if it were made with potatoes alone.

Ingredients:

One head of cauliflower, cut into florets/bit-sized chunks
5 medium-sized russet or Yukon Gold potatoes, peeled and cut into thick slices or chunks
3 T butter
1 onion, diced
3 T sweet rice flour
1 C heavy cream
1 - 2 C milk
Shredded cheese (Gruyere, cheddar, Gouda, whatever) - approx 3+ Cups
1/2 tsp dry mustard
salt
Lawry's seasoned pepper

Directions:

Place the potato and cauliflower pieces into a large pot and add enough water to cover; bring to a boil then turn down heat and simmer for 10 minutes. You want the potato and cauliflower chunks to be cooked through but still firm, not mushy. Drain thoroughly and dump the pieces into a large buttered casserole dish or 13" by 9" pan.

While the potato and cauliflower pieces are cooking, prepare the cheese sauce: melt butter in a large skillet and add the diced onion. Saute the onion until translucent and soft, about 5 minutes. Add a bit more butter if needed, then add the sweet rice flour and dry mustard to make a thick paste. Pour in the heavy cream, stirring vigorously over low heat. This will thicken rapidly; add milk, stirring constantly, a little bit at a time, until the sauce is about the consistency of paint, maybe a bit thinner. Remove from heat and add cheese; reserve some cheese for the top. I tend to use a LOT of cheese, but you can adjust the amount to your personal tastes. Add salt and pepper to taste.

Pour the sauce over the potatoes and cauliflower pieces in the casserole dish; top with extra cheese and bake at 350 degrees for about 30 - 35 minutes, until bubbling around the edges and beginning to brown slightly on top.

Yum!!