Pre-heat oven to 350F (180C). Lightly grease and flour an 8x8 inch (20x20cm) square cake pan or line with parchment paper.
SHORTBREAD BASE
In a medium bowl, beat on medium speed the butter and powdered sugar until combined then add the flour and beat again until a soft dough forms (approximately 1 1/2 minutes). Pat evenly onto the bottom of the prepared baking pan. Bake 18-20 minutes. Remove from oven, but leave oven on.
LEMON FILLING
Meanwhile in a medium bowl, beat together, the eggs, granulated sugar, baking powder, fresh lemon juice, pinch of salt and zest. Pour over warm v (not hot) baked base and return to the oven for 20-25 minutes (until the centre is set, I baked mine for 25 minutes, may need to go a bit longer), Cool in the pan, I recommend that you also chill in the fridge for 1 hour for easier cutting, cut into squares, remove from pan, dust with powdered sugar and serve. Enjoy!
Notes
You may want to refrigerate the Lemon Bars before cutting as it makes cutting the squares easier.You know when Lemon Bars are done when you gently shake the pan and the filling is set and no longer jiggles. Store the cooled baked bars in an airtight container in the fridge, although they can be left out for a few hours while they are being served. They will last up to 4 days in the fridge.Lemon Squares can also be frozen, place the completely cooled cookies, on a cookie sheet, freeze for 1 hour then transfer to a freezer safe container, place parchment paper between the layers, they will keep for up to 3-4 months in the freezer.Be sure to thaw the frozen cookies in the fridge before serving. If you do freeze them, don’t dust with powdered sugar first, that can be added before serving.