Preheat the oven to 325°F with a rack in the center position. Lightly grease a 9" x 5" loaf pan., Using an electric or stand mixer, beat together the butter and cream cheese at high speed until they're very light and fluffy., Add the salt, sugar, flour, and baking powder, and mix to combine; the batter will be stiff., Add the extracts and 1 egg. Beat well. Continue to add the eggs one at a time, beating well after each addition; the finished batter should be extremely light and fluffy., Spoon the batter into the prepared loaf pan., Bake the cake for 85 to 90 minutes, tenting it lightly with aluminum foil after 60 minutes, until a toothpick inserted into the center comes out clean., Remove the cake from the oven, and after 5 minutes turn it out of the pan to cool on a rack., Serve the cake warm or at room temperature; dust it lightly with confectioners' sugar just before slicing, if desired., Store the cake, well-wrapped, at room temperature for several days; freeze for longer storage.