Preheat oven to 350°.
To make the crust, cream the butter in a mixing bowl at high
speed. Add flour, sugar & lemon extract. Mix at low speed until well blended.
Press the dough with your fingertips into an ungreased 8x8 inch glass baking
dish. Press dough evenly up sides of the pan about an inch. The crust should be
of even thickness. Bake the crust at 350° for about 20 minutes, until golden.
In a separate bowl, mix flour and baking powder. Add to the mixing bowl, beat lightly until combined.
Spread the filling onto the hot crust (there should be visible crust around the edges of pan).
Return pan to oven and bake about 30 minutes. Remove from oven and let cool thoroughly (at least 1 hour) before cutting.
Slice, then sift powdered sugar all over the top.
Remove sliced bars from pan, and store in airtight container.