These lightly spiced muffins are a welcome addition to any holiday breakfast or brunch — tender, flavorful and moist (and they freeze well, too). If you're pressed for time, you can substitute an equal amount of canned sweet potatoes or even canned pumpkin for the sweet potato purée.
Technically, Old World yams and New World sweet potatoes are indeed different vegetables. In the US today, the terms are most often used interchangeably to describe popular varieties of red-skinned, orange-fleshed tubers with pointed ends. At Earthbound Farm we produce organic Garnet and Jewel varieties, which are commonly called yams but are actually sweet potatoes. No matter what you call them, though, they're delicious!
Steam the yams on a rack or in a steamer basket over boiling water until very tender, 20 to 30 minutes. Mash or press the yams through a sieve to create a smooth purée. You need 1 cup of purée for this recipe; extra purée can be frozen.
Position a rack in the lower third of the oven and preheat to 400 degrees F. Line a standard 12-cup muffin tin with paper liners.
Blend the 1 cup of yam purée with the sour cream, egg, butter, and milk in a small bowl and beat with a wooden spoon until smooth.
In a separate bowl whisk together the 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 the batter is just combined; don't overmix or your muffins will be tough. The batter will be thick.
Scoop or 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 to 20 minutes. Set pan on wire rack to cool.