Add the vanilla extract and mix well.

Bake for 35-40 minutes or until lightly golden.

Gradually add the flour and salt to the mixture, stirring until a crumbly dough forms.

In a medium bowl, beat together the softened butter and sugar until light and fluffy.

Preheat the oven to 300°F (150°C). Lightly grease two 9-inch round or 8-inch square cake pans.

Press the dough into the prepared pans, smoothing it with your hands.

Remove from the oven and let it cool in the pan for 10 minutes.

Use a fork to prick the dough all over to prevent bubbles.

While still warm, cut the shortbread into wedges or squares.