Preheat oven to 325 F. Line bottom of a 9"x5"x3" loaf pan with parchment paper; grease sides of pan.
In a large bowl, beat the butter, syrup and sugar until smooth with electric mixer.
In a medium bowl, combine flour, baking soda and cocoa. Beat 1
tablespoon of the dry ingredients into the syrup mixture; then beat in 1
egg. Add another couple of spoonsful of dry ingredients before adding
the last egg.
Beat in remaining dry ingredients and the lemon yogurt base.
Pour batter into the prepared pan and bake for 45 minutes (edges should
look dry and the center of the cake may have dipped slightly). Cool
cake in pan on wire rack.