Preheat oven to 350 degrees F. Wrap the outside of a 9 inch springform pan with aluminum foil to prevent leaking. Sift together the flour, orange zest, baking powder, baking soda, cinnamon and salt. Set aside.

In a saucepan over medium heat, combine brown sugar and 1/2 cup butter. Bring to a boil, then add cranberries, pecans, and orange zest, stir, and pour into bottom of springform pan. Do not overcook the sugar mixture.

In a large bowl, cream together the butter and 3/4 cup sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Beat in the flour mixture alternately with the sour cream. Pour batter into prepared pan.

Bake in the preheated oven for 60 minutes, or until a toothpick inserted into the center of the cake comes out clean. Cool in pan for 10 minutes, then invert onto serving platter and carefully remove pan. Serve warm.