Roasted Sweet Potatoes with Red Onions, Rosemary, and Parmesan

I got this recipe (and photo) from Kalyn's Kitchen and adapted it to fit my circumstances. I used 1 golden potato, 1 red, and 2 sweet potatoes, dried rosemary and parsley, and regular parmesan from the canister and I put all the spices on before baking. Also, I found out afterwards that I would have preferred to cover the potatoes with foil for 1/2 the baking time and let them crisp up in the 2nd half. The onions were charred and the potatoes were a little crispier than I like.
Roasted Sweet Potatoes with Red Onions, Rosemary, and Parmesan
(Makes 4 servings, slightly adapted from Bon Appetit, November 2002)

4 large or 6 medium tan-fleshed sweet potatoes (white skin)
3 medium red onions
3 T olive oil
2 T finely chopped fresh rosemary, divided (I used my frozen rosemary, if you only have dried rosemary use less and make sure it's finely chopped)
1 tsp. salt (I used McCormicks Mediterranean Spiced Sea Salt, which was great in this)
fresh ground black pepper to taste
1/2 cup fresh grated parmesan cheese
2-3 T chopped fresh parsley (optional)

Preheat oven to 375 F and cover a flat roasting pan with foil, then spray foil with non-stick spray or mist with olive oil.

Peel potatoes and remove skin from onions. (Sweet potatoes could also probably be left unpeeled, but I did peel them.) Cut sweet potatoes and onions into same-size pieces about 1 inch square. Place in plastic bowl and toss with olive oil, 1 T chopped rosemary, salt or sea salt, and fresh ground black pepper. Arrange in single layer on roasting pan and roast until vegetables are cooked through and slightly browned, about 45 minutes or longer. (I actually roasted my sweet potatoes and onions in the photo for about exactly an hour, but I like them a little crisp and well-browned.)

Combine fresh-grated parmesan and finely chopped rosemary in small bowl. Remove vegetables from oven and toss with parmesan-rosemary mixture. Serve hot, sprinkled with fresh parsley if desired.