Semi Sweet Potato Mash With Caramelized Onions

• 1 pound russet potatoes, peeled and diced
• 1 pound sweet potatoes, peeled and diced
• 1 large sweet vidalia or Spanish onion, halved and thinly sliced
• 1 tablespoon olive oil
• 1 tablespoon butter
• Pinch cayenne pepper
• Pinch freshly ground nutmeg
• Sea salt & pepper

1. In a large saucepan, cover the potatoes with cold water. Bring to a boil over high heat. Simmer until the potatoes are fork tender, about 10 to 15 minutes. Drain and return to the pot. Using a masher or fork, crush the potatoes until no chunks remain. Whisk in the butter and season to taste with the cayenne, nutmeg, and salt.
2. Meanwhile, heat the oil in a large cast iron skillet. Saute the onions over medium-high heat until soft and beginning to brown, about 8 minutes. Reduce the heat to medium-low and continue to cook the onions, stirring occasionally, until very browned and caramelized, about 30 minutes. This is a low and slow process and shouldn't be rushed - your onions will be about 1/4 of the size they were at the beginning. Season to taste with salt and pepper.
3. Transfer the potatoes to a casserole dish and top with the caramelized onions. Can be make 2 days ahead and reheated in a 350 degree oven.

potatoes, sweet potatoes, sweet vidalia, olive oil, butter, cayenne pepper, freshly ground nutmeg, salt

Taken from food52.com/recipes/25471-semi-sweet-potato-mash-with-caramelized-onions (may not work)