Combine the first 5 (dry) ingredients in a mixing bowl and stir together. Make a well in the center and pour in the yogurt or applesauce, orange juice, optional zest, and oil. Add a small amount of orange juice if need be to loosen the batter a bit, but let it remain stiff. Stir just until well combined.
Place the cranberries in a food processor and pulse on and off until coarsely chopped. Stir in the sugar and let the mixture stand for a couple of minutes.
Stir the cranberries into the batter.
Divide the batter evenly among 12 foil paper-lined muffin tins or 3 to 4 mini loaf pans (depending on their size). If using nuts, scatter over the tops of the muffins evenly.
Bake for 20 to 25 minutes, or until the tops are golden and a knife inserted into the center of one tests clean. When the muffins are cool enough to handle, transfer them to a plate or rack to cool.