Preheat oven to 350°

Using an electric handheld mmixer, cream butter and sugar together in a small bowl until light and fluffy - about five minutes.

Slowly add in flower until blended.

Press dough into an ungreased 8 x 8 inch baking dish, and evenly spread out in bottom of pan to a thin crust.

Place in oven and bake for 20 - 25 minutes or until the edges of the crust are a light golden brown.

In a large bowl using an electric handheld mixer, beat sugar, eggs, lemon juice, flour, lemon zest and baking powder until frothy and pour over the hot crust.

Bake for 15 - 20 minutes or until set and golden brown. Remove baking pan from oven and cool on a wire rack for ten minutes.

Sprinkle with powdered sugar and cut into equal squares.