01 - Gently melt the butter with the whole milk in a saucepan over low heat. Add the sugar and vanilla, stirring continuously until the sugar has fully dissolved and the mixture is smooth.
02 - Remove the saucepan from the heat and allow the mixture to cool slightly until lukewarm. Transfer the warm liquid into a large mixing bowl.
03 - Add the all-purpose flour, baking powder, and salt to the mixing bowl. Stir with a wooden spoon until a homogeneous dough forms and no dry patches remain.
04 - Shape the dough into a smooth ball, wrap it tightly in plastic wrap, and refrigerate for 1 hour to firm up and make it easier to roll.
05 - Preheat the oven to 350°F using conventional (static) heat mode.
06 - On a lightly floured work surface, roll the chilled dough out to an even thickness of approximately ⅛ inch (3 to 4 mm).
07 - Using a traditional fluted rectangular cookie cutter, cut out the biscuits and carefully transfer each one to the prepared baking sheet.
08 - Arrange the cut biscuits on a baking sheet lined with parchment paper. Gently prick each biscuit several times with a fork to create the classic pattern and prevent air bubbles.
09 - Bake on the middle rack for approximately 12 minutes, or until the edges and tops are evenly golden brown.
10 - Transfer the biscuits to a wire cooling rack and let them cool completely before serving. They will crisp up as they cool.