Old time bakers used to make a "pudding" for chocolate cakes. This pudding is different than the pudding in the mix chocolate cakes we are used to today. Old time chocolate pudding was a way for bakers to elicit the full chocolate flavor from the cocoa powder and unsweetened chocolate which gave them rich full flavored chocolate cake.
When cakes are made strictly with cocoa powder which contains mostly cocoa solids the chocolate cake flavor is somewhat subdued. The chocolate flavor can be stricken even more by mixing the cocoa powder with flour. But by incorporating unsweetened chocolate which contains cocoa butter as well as cocoa solids into the cocoa powder the chocolate cake is given an extra boost of chocolate flavor.
Water and sugar also play an important role in making a rich full flavored chocolate cake. Hot water heated in a double boiler is used to bloom the chocolate flavor in the cocoa powder and unsweetened chocolate. Then when sugar is incorporated into the chocolate pudding the subtle chocolate flavors will begin to shine.
Here is the basic recipe for making a pudding to add to your chocolate cake batter.
Combine coarsely chopped unsweetened chocolate, cocoa powder, and hot water in a double boiler. Heat until the chocolate is melted. Then add the sugar and stir until the pudding is glossy and thick.
Simply adjust the amounts above to your favorite chocolate cake recipe and watch your cake take on a whole new level of sweet chocolate flavor.