Preheat oven to 350 degrees and lightly grease a 9x13 pan.
Using your mixer with the paddle attachment, cream together the butter, oil and both sugars until smooth. Add the egg, water, vanilla and almond flavorings then beat until smooth. Add the flour, salt, baking powder and soda then beat until completely combined.
Use a rubber spatula and evenly spread the batter in the greased pan. Sprinkle another tablespoon of sugar over the top before putting in the oven for 14-16 minutes. You want the edges of the bars to just barely start to turn brown.....just barely! If you overcook them, they will be dry and crumbly. Allow the bars to cool completely before frosting.
While the bars cool, beat together all the ingredients for the frosting and once the bars have cooled, frost the bars before slicing.