01 - Gently melt the butter with the whole milk in a small saucepan over low heat. Add the granulated sugar and vanilla seeds scraped from the pod, stirring continuously until the sugar has fully dissolved and the mixture is smooth.
02 - Remove the saucepan from heat and allow the butter-milk-sugar 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 or spatula until a smooth, homogeneous dough forms and no dry pockets of flour remain.
04 - Shape the dough into a tight ball, wrap it securely in plastic wrap, and refrigerate for at least 1 hour to firm up the butter and make the dough easier to roll.
05 - Preheat the oven to 350°F using conventional (static) bake mode. Position the rack in the center of the oven.
06 - Lightly flour a clean work surface and roll out the chilled dough to an even thickness of approximately 1/8 to 3/16 inch using a rolling pin. Rotate the dough frequently to prevent sticking.
07 - Using a traditional fluted rectangular cookie cutter, cut out the biscuits from the rolled dough. Re-roll scraps and continue cutting until all the dough is used.
08 - Place each cut biscuit onto a baking sheet lined with parchment paper, leaving about 1 inch of space between them to allow for slight spreading.
09 - Gently prick each biscuit several times with a fork to create the classic petit beurre pattern and prevent air bubbles. Bake on the center rack for 12 minutes, or until the edges and tops turn a lovely golden color.
10 - Transfer the baked biscuits to a wire cooling rack immediately and let them cool completely before serving or storing. This ensures they develop their signature crisp texture.