01 - In a small saucepan over low heat, gently melt the butter with the whole milk. Add the sugar and scraped vanilla bean seeds, stirring continuously until the sugar has fully dissolved and the mixture is smooth.
02 - Remove the saucepan from heat and allow the butter-milk mixture to cool slightly until lukewarm, then transfer it to a large mixing bowl.
03 - Add the all-purpose flour, baking powder, and fine sea salt to the wet mixture. Stir with a wooden spoon until a homogeneous dough forms and no dry pockets of flour remain.
04 - Shape the dough into a smooth ball, wrap it tightly in plastic wrap, and refrigerate for at least 1 hour to firm up and make it easier to roll.
05 - Preheat the oven to 350°F using conventional bake mode (no fan). Line a baking sheet with parchment paper and set aside.
06 - On a lightly floured work surface, roll the chilled dough out to an even thickness of approximately ⅛ inch (3 to 4 mm), rotating the dough frequently to prevent sticking.
07 - Using a traditional fluted rectangular cookie cutter, cut out as many biscuits as possible from the rolled dough. Re-roll any scraps and continue cutting until all the dough is used.
08 - Place each cut biscuit onto the prepared baking sheet, leaving about ½ inch of space between them. Gently prick each biscuit several times with a fork to create the classic dotted pattern and prevent air bubbles during baking.
09 - Bake on the center rack for 12 minutes, or until the edges turn a light golden brown. Rotate the baking sheet halfway through for even browning.
10 - Transfer the biscuits to a wire cooling rack immediately and allow them to cool completely before serving or storing. The biscuits will crisp up as they cool.