The BEST of both worlds --make mashed sweet potatoes AND regular mashed potatoes in one dish (the slow cooker). Now you can serve both potatoes easily to your guests at Thanksgiving. OR for a super delicious side dish, swirl the two crockpot mashed potatoes together.
Peel the red potatoes (or leave skin on if preferred, I peeled them) and sweet potatoes. Cut all of the potatoes into equal sized large chunks.
Spray a large crockpot (I used a 6-quart crockpot) with non-stick spray or use a crockpot liner if desired.
Place the red potato chunks on one side of the crockpot and the sweet potato chunks on the other side of the crockpot.
Generously salt and pepper all of the potatoes. Pour the water over the potatoes and shake the crockpot to get the water evenly distributed throughout.
Cover and cook on high for 3-4 hours or until both the sweet potatoes and the red potatoes are very tender. My crockpot had both tender in about 3 and 1/2 hours.
With a slotted spoon, remove the sweet potatoes into a separate bowl.
Leave the red potatoes in the crockpot and drain out any liquid (or remove the red potatoes to another bowl, but I like to save a bowl from getting dirty and prepare them in the crockpot!)
Place three tablespoons butter and the brown sugar into the bowl with the sweet potatoes.
Using hand mixers, beat until completely smooth. Season additionally with salt and pepper to taste.
In the bowl with the red potatoes, place the remaining three tablespoons of butter, the sour cream, and the milk or heavy cream (I use heavy cream), and the garlic powder.
Using hand mixers, beat until completely smooth.
IF serving the potatoes separately add whatever toppings you enjoy (sweet potatoes: pecans, extra spices, sea salt, etc.) (red potatoes: chives, parsley, shredded cheddar cheese, bacon, etc.)
Otherwise, swirl the two different potatoes together in one large dish and enjoy.
Notes
All crockpots cook differently so make sure to watch yours carefully to make sure the potatoes don't burn. If you have an older crockpot it may take a long time to cook the potatoes. I use a 6-quart crockpot.