1 cup of mashed, cooked sweet potato (from 1 pound of sweet potatoes or about 2 big ones)
½ cup sour cream
1 large egg
½ cup (1 stick) butter, melted
1/4 cup milk
1½ cups all-purpose flour
1 cup light brown sugar, packed
2 teaspoons baking powder
1 teaspoon baking soda
1 tablespoon pumpkin pie spice
¼ teaspoon salt
¾ cup fresh or frozen cranberries, coarsely chopped
Position a rack in the lower third of the oven and preheat to 400◦ F. Line a standard 12-cup muffin tin with paper liners.
Press the mashed sweet potato through a sieve to create a smooth puree. Mix the 1 cup of sweet potato with the sour cream, egg, butter, and milk in a bowl and beat with a spoon until smooth. In a separate bowl whisk together flour, sugar, baking powder and soda, spice, and salt. Add the flour mixture to the liquid ingredients, and stir until partially combined. Add the cranberries and stir until batter is just combined; do not overmix or muffins will be tough. Batter will be thick.
Spoon the batter into the prepared muffin tins, filling to the brim. Bake until muffins are golden and spring back when lightly pressed, about 15 - 20 minutes. Set pan on wire rack to cool.
These muffins are moist and freeze well.