Combine dry ingredients in a medium mixing bowl. Work butter into dry ingredients using a pastry blender or fork until butter is the size of small peas.
Combine cranberries, mashed banana, walnuts and egg in a medium mixing bowl. Add to dry ingredients, mixing thoroughly.
Spoon batter into a 10-inch circle on an un-greased cookie sheet. Cut into 8 wedges. Bake for 25 minutes. Serve warm.
