Peel and cut the sweet potatoes into one inch cubes. Place them in a medium pot and cover with water.
Bring the pot up to a boil. Continue to boil the potatoes until a fork inserts easily into the potatoes (about 7-10 minutes). Drain the potatoes in a colander and return them to the pot (turn off heat). While the potatoes are boiling, roughly chop two chipotle peppers.
Add the milk, butter, brown sugar and chipotle peppers to the potatoes. Mash and mix the ingredients until smooth. Taste and add salt and pepper to your liking.