Mix butter and powdered sugar until combined.

Add grated lemon peel and flour to the butter mixture.

Mix well until a dough forms.

Press the dough evenly into a well-buttered 9x13-inch pan.

Bake in a preheated oven at 350F (175C) for 20 minutes, or until lightly golden.

While the shortbread is baking, beat eggs until light and fluffy.

Gradually add sugar to the eggs, beating until thick and pale.

Add grated lemon rind, flour, and baking powder to the egg mixture.

Mix until well combined.

Stir in lemon juice until smooth.

Pour the lemon mixture evenly over the baked shortbread crust.

Return the pan to the oven and bake for another 15-20 minutes, or until the filling is set and golden brown on top.

Remove the lemon bars from the oven and let them cool completely in the pan.

Once cooled, sprinkle generously with powdered sugar.

Cut into bars and serve.