Here is the recipe from Miss Mary Bobo's Boarding House Cookbook.

Tispy Sweet Potatoes

4 large sweet potatoes
1/4 cup butter, softened
3/4 cup sugar
1/8 tsp. salt
1/4 cup Jack Daniel's Whiskey
1/2 cup broken pecans, lightly toasted

In a large pan cook the unpeeled sweet potatoes in just
enough water to cover completely. Bring to a boil, cover,
and cook until tender, about 35 minutes. Drain and cool,
then peel off the skins. In a mixing bowl mash the potatoes
with the butter. Add the sugar, salt, and Jack Daniel's Whiskey.
In a buttered 1 1/2-quart round casserole dish, spread half
of the potatoes and sprinkle with half the pecans. Repeat
layers. Bake at 325 until hot, about 30 minutes.

Note: Light brown sugar may be substituted for
white sugar to give a different (caramel) taste to this dish.
Yield: 6 to 8 servings.