Costco make a cake called the Tuxedo Chocolate Mousse Cake. It is very good. If you like dark chocolate I can't think of anything tastier than this delicacy.
I've been trying to work out what makes it taste so good. When reading the ingredients I came across the leavening: Sodium Bicarbonate, Sodium Acid Pyrophosphate, Sodium Aluminum Phosphate, Monocalcium Phosphate.
Digging a bit deeper I see that the Sodium Aluminum Phosphate is synthetically produced from aluminum, phosphoric acid and sodium hydroxide. As a food additive is has the E number E541.
It has to be the Sodium Aluminum Phosphate that gives it that thick, dark, creamy rich texture and taste...