Spinach + Sweet Potato Gratin

I found this recipe from Smitten Kitchen and her description was dead-on for how I feel about eating such yumminess as mashed potatoes. I also had just read this article ("Like this? Eat that") basically saying if you liked certain common veggies you might try some other ones similar to them for more vitamins/nutrients, etc...one example being spinach, try swiss chard. And since I'm trying to incorporate more veggies into our meals but also maintain my caloric needs I thought this sounded like a great compromise.

It's not the most appetizing-genic food but Deb made it look prettier. The final result was interesting and delicious. Not what I had expected but quite tasty and a nice change of veggie pace.

I could not find swiss chard so I used frozen chopped spinach. Here's my 1/4rted version of the dish:
2.5 Tbsp butter (divided)
1/4 c finely chopped onion
1 10-oz pkg frozen, chopped spinach--thawed and drained
good pinch nutmeg
1/2 c milk (2%)
1 clove garlic, minced
2 tsp flour
2 med-large sweet potatoes, peeled and sliced into 1/8" rounds
1-2 Tbsp dried parsley
1-2 tsp dried thyme
3-4 oz smoked gyuere, shredded (keep about 1-2 oz aside for the top of the dish)
salt/pepper
1. preheat oven 400F, grease 8x8 pan.
2. In non-stick skillet melt 1 Tbsp butter; sautee spinach, onion, nutmeg, salt/pepper--set aside
3. In bowl, heat milk and garlic in microwave til it's warm and aromatic
4. In small sauce pan melt 1.5 Tbsp butter, whisk in flour and con't whisking for 1 min.--remove from heat. slowly add in the milk mixture til smooth. season with salt and pepper.
5. Cover bottom of pan with layer of 1/2 potatoes. then 1/4 herbs, 1/4 cheese, 1/2 spinach mixture, 1/4 herbs, 1/4 cheese, 1/2 milk mixture; remaning potatoes, etc...top the final product with about 1/2 the cheese.
Bake 30-45 min (covered) til bubbly and brown...remove foil for last 5-10 min for desired browness.