Preheat the oven to 325°F. Grease and flour a 10" tube pan or a 12-cup bundt-style pan., In a large mixing bowl, beat the butter until it's soft. Add the sugar, salt, baking powder and flavorings. Beat them together until well-blended., Add the flours and mix; the mixture will be crumbly., Add the eggs one at a time, scraping the bottom and sides of the bowl after each addition. The batter will become fluffy after the third or fourth egg has been added., Scrape the batter into the pan, and level it with a spatula., Bake the cake for 1 hour (or longer), until a tester inserted in the center comes out clean, and the edges pull away from the pan., Remove the cake from the oven, and place it on a rack to cool. Turn it out of the pan after about 10 minutes to cool completely., To make the glaze, mix all of the glaze ingredients together, adding a bit of water if needed to make it spreadable., Use a spatula to spread it over the top of the cake. Let the glaze set for a few minutes before serving., Store, covered, for up to a week at room temperature, or freeze for up to 3 months.