Spray bottom of 9-inch spring-form pan with non-stick spray.

In a medium bowl, combine flour, baking powder, baking soda and salt.

In a separate larger bowl, beat butter with sugar until light and fluffy. Add egg. Stir in vanilla, yogurt, and lemon peel. Stir in flour only until blended.

Remove 1 cup of the batter and set aside. Use a spatula to spread remaining batter evenly in prepared pan.

Into the 1 cup of batter, gently stir blueberries. Spread this as a top layer over the batter in the pan.

Bake in preheated oven for 40 minutes or until the center of cake springs back when lightly touched and the cake is golden brown. Do not open oven until at least 35 minutes have passed.

Cool on a wire rack. When cake has cooled for 5 minutes, run a blunt knife along edges of pan to free cake; remove from pan and allow to cool completely.

To make glaze, combine confectioners' sugar, lemon juice and softened butter (a drop of vanilla or lemon extract may be added for extra flavor). Drizzle over cooled cake.

Variation: This same batter can be used for muffins. Bake muffins for about 20-22 minutes or until a wooden pick inserted in center comes out clean.

Submitted by: CM