01 - Gently melt the butter with the whole milk in a saucepan over low heat. Add the sugar and scraped vanilla seeds, stirring continuously until the sugar has fully dissolved.
02 - Remove the saucepan from heat and allow the mixture to cool until just warm to the touch, then transfer it to a large mixing bowl.
03 - Sift the all-purpose flour and baking powder directly into the bowl. Add the pinch of salt and stir with a wooden spoon until a smooth, homogeneous dough forms.
04 - Shape the dough into a ball, wrap it tightly in plastic wrap, and refrigerate for at least 1 hour to firm up for easier rolling.
05 - Preheat the oven to 350°F (180°C) using conventional bake setting. Line a baking sheet with parchment paper.
06 - On a lightly floured work surface, roll the chilled dough out to an even thickness of about ⅛ inch (3–4 mm), rotating occasionally to prevent sticking.
07 - Using a traditional fluted rectangular cookie cutter, cut out the biscuits and carefully transfer each one to the prepared baking sheet, leaving a small gap between them.
08 - Gently prick each biscuit several times with a fork to prevent puffing. Bake on the middle rack for 12 minutes, or until the edges turn a light golden brown.
09 - Transfer the biscuits to a wire cooling rack immediately and let them cool completely before serving. They will crisp up as they cool.