Lemon Shortbread Squares

INGREDIENTS

SHORTBREAD CRUST:

1 cup

salted butter, softened to room temperature

3/4 cup

icing sugar/confectioners' sugar

1/2 cup

granulated sugar

1/2 tbsp

vanilla extract

2 cups

all-purpose flour

FILLING INGREDIENTS:

large eggs at room temperature

3/4 cup

granulated sugar

1 tbsp

grated lemon zest (1 to 2 lemons)

1/3 cup

freshly squeezed lemon juice (~ 1 large lemon)

1/3 cup

all-purpose flour

TOPPING (optional):

1/3 cup

white chocolate chips or melting chocolate