Shred stick of butter, place in a bowl, and back in the fridge until we will need it in the recipe. You can use a grater, or just cube it into small cubes.
Preheat your oven at 450 degrees F.
In a large bowl, combine all-purpose flour, sugar, baking powder, and salt. Mix well.
Add onion and cheese. Mix until onion and cheese are coated in flour.
Take the shredded butter out of the fridge and add to the flour mix.
With 2 forks mix the flour and butter (or use a pastry cutter). Don’t overmix. It will be a coarse mix.
In a small bowl beat the egg then add it to the dough with the milk too. Mix until all ingredients are incorporated.
On a floured surface, knead the dough for 2 to 3 minutes. It will be a sticky dough to the touch, but your fingers should be clean. NOTE: You may need to add more flour, (between 1/8 to ¼ cup) but be careful not to add too much as you need that slight stickiness for the biscuit.
Roll the dough to about ¾ inch of thickness.
Cut 8 biscuits, gathering & re-rolling dough if necessary. (I used a 2 ¾ inch diameter circle cutter). (TIP: If you have leftover pieces of dough and can't fit another biscuit, divide the dough between all 8 biscuits and add the dough to the underside of the biscuits, so that the tops still bake up pretty!)
Place on a baking sheet, ungreased, and bake for 10 minutes at 450°F or until lightly golden. Turn oven off and let the biscuit sit for 2 minutes in the oven.