Beat butter and sugar until frothy, add eggs. Mix the yogurt and lemon juice and zest. Mix the flour, baking powder, salt, cinnamon and vanilla together. Now alternately add yoghurt and dry ingredients to the egg mixture. Put the dough in a piping bag and fill the mini Gugelform.
Bake for about 10 - 15 minutes, make a stick test.
Let the mini Gugel cool and then dust with powdered sugar.
Mix the icing with powdered sugar and a dash of lemon juice and decorate the Gugel with it, sprinkle with pistachios if necessary.