ham and root vegetable au gratin

My CSA vegetable deliveries are over, but I still have a variety of root vegetables languishing in the frig. I don't *love* some of them like beauty heart radishes, turnips, or parsnips so I like to try recipes that will mellow their flavor a bit. I got a delicious Christmas ham from Prairie Pride Farms and didn't want to make the standard ham and bean soup with the leftovers, so I went looking for gratin recipes and this is what I came up with:

4 medium carrots
2 medium parsnips
1 medium turnip
2 medium potatoes
1 medium sweet potato
3 cups ham, diced
1 medium onion
1 large clove garlic, minced

Peel and thinly slice all the vegetables. Set aside. Saute sliced onion and garlic in butter on low heat. While sauteing, make the sauce in a separate pan.

Sauce:
3 tablespoons butter
3 tablespoons flour
1/2 teaspoon salt
2 cups milk
1 1/2 cups shredded cheese (I used a super tasty Gouda from Whole Foods)

Melt butter and add flour and salt, whisking your roux until it's nice and bubbly. Pour in milk and cook until thickened. Remove from heat and stir in cheese.

Mix vegetables, ham, and onions and garlic together in a large baking dish. Pour sauce over mixture and stir well. Season with salt and pepper. Bake at 350 for 45-55 minutes, until bubbly and you can pierce the vegetables with a fork. Add a bit more shredded cheese on top towards the end.