Preheat your oven to 325°F (165°C) and line an 8x8-inch baking pan with parchment paper.

In a stand mixer or bowl, add softened butter, granulated sugar, vanilla extract, and kosher salt. Beat for about 2 minutes until creamy.

Gradually mix in the all-purpose flour at low speed until fully combined, ensuring not to overmix.

Transfer the dough into the prepared baking pan and press evenly to about ½ inch thickness. Cover with plastic wrap.

Dock the surface of the dough with a fork, make about 36 pricks. Chill the pan in the refrigerator for 30 minutes.

Bake in the preheated oven for 30-35 minutes until golden brown and firm to the touch.

Let the biscuits cool for a few minutes, then slice into rectangles while still warm.

Transfer the sliced biscuits to a wire rack to cool completely before serving.