Preheat the oven to 350F degrees.
Place the pre-sliced sweet potatoes in a saucepan with enough water added to boil. Bring to a boil and cook until tenderized for about 15 minutes.
When done, remove the saucepan from the heat and drain the water. Mash the sweet potatoes as desired.
Place sweet potatoes in a bowl, and add margarine, brown sugar, and cinnamon. Use an electric mixer to blend potatoes with other ingredients.
Spread potatoes evenly across a 9

5 sweet potatoes, sliced (typically no less than 4 large tubers to begin with)