Begin by preheating your oven to 425°F (220°C).

In a large mixing bowl, whisk together all-purpose flour, baking powder, and salt until well combined. Cut in cold, unsalted butter until the mixture resembles coarse crumbs. Gradually stir in buttermilk until the dough just comes together.

Turn the dough out onto a lightly floured surface. Gently knead the dough a few times, then roll it out to a thickness of about 1 inch. Cut out biscuits and place them on the prepared baking sheet.

Take half of the cut biscuits and layer them with slices of roast beef and Swiss cheese. Place the remaining biscuits on top, pressing down gently to seal the edges.

Slide the baking sheet into the preheated oven and bake for 15-20 minutes until golden brown.

While the biscuits bake, combine beef broth, Worcestershire sauce, garlic powder, and onion powder in a saucepan. Simmer for about 5 minutes, stirring occasionally.

Once baked, remove the biscuits and allow them to cool slightly. Serve warm with au jus for dipping.