Preheat oven to 400 degrees. Line a baking sheet with parchment paper or lightly oil.
Cut butter into small chunks and add to a large mixing bowl. Add flour, salt, and baking powder.
Using a fork or your fingers, begin to mix butter into the flour until you have a crumbly mixture.
Stir milk and mayo into the flour mixture until just combined.
Drop round golf ball sized balls of dough onto your baking sheet.
Bake biscuits for 15-20 minutes until lightly golden. Transfer to a cooling rack to let cool or serve immediately!