Grate the parmesan cheese.
In a food processor, carefully attach the metal processing blade. Add flour, baking powder and salt. Pulse a few times to mix up.
Add the parmesan cheese to the food processor. Give it a quick pulse.
Cut the cold butter into 1-inch sized cubes. Add it to the food processor and pulse.
In a medium bow, mix wet ingredients together.
Add to the wet mixture to the food processor and pulse, then add the crushed sage.
Make sure the dough is cohesive.
Carefully add the dough to a well-floured work surface. Lightly knead a few times.
Roll out to about 1-inch thick.
Use a circle cookie cutter to cut out the biscuits.
Transfer the rounds to a baking sheet lined with parchment paper.
Whip up a quick egg wash by adding one egg and some milk to a small bowl. Whisk until combined.
Brush the egg wash on the tops of the biscuit.
Transfer to the oven to bake at for about 14 - 20 minutes.
Serve with nice butter.