1Preheat oven 325 deg. Butter and flour a 10 inch bundt pan.Sift the dry ingredients together.Set aside, beat the butter and sugar in a large bowl on high speed until light and fluffy about 3 minutes, beat in eggs one at a time then the vanilla and zest. On low speed add the flour mixture alternating with the sour cream beat until smooth scraping down the sides of the bowl often with a rubber spatula, spread evenly in the pan. Bake for about 1 hour.
For the glaze,combine all ingredients together,beat until smooth.Drizzle on top of cake letting glaze drizzle down the sides.