Special equipment: A few 4-ounce cup muffin pans; ribbed paper cupcake liners
Make the Cake. Preheat the oven to 350 degrees F.
Line the muffin tins with paper liners.
In a mixer fitted with a paddle attachment (or using a hand mixer), cream the butter until smooth. While the mixer is running, slowly add the sugar. Add the eggs one at a time, waiting for each to be incorporated before adding the next, and mix until light and fluffy.
Sift together the flour, baking soda, baking powder, and salt. Working in batches, add the flour mixture to the butter-sugar mixture, alternating with dollops of sour cream. Mix in the cranberries. Pour or spoon the batter into the prepared tins, filling them no more than 3/4 full.
Make the Topping: Combine the brown sugar, flour, and cinnamon in a medium bowl. Add the butter pieces and, using your fingertips, pinch the ingredients together into a sandy, crumbly mixture. Add the walnuts and mix. Sprinkle the mixture over the cakes.
Bake until risen and browned, about 20 to 25 minutes. Let cool 10 minutes in the pan.
Recipe courtesy of Gale Gand, Gale Gand's Just A Bite by Gale Gand and Julia Moskin: Clarkson N. Potter Publishers, 2001