Preheat the oven to 500 degrees F.
Whisk together flour, salt, and baking powder in a medium-sized bowl.
Cut the cold butter and cream cheese into the flour mixture until it resembles coarse crumbs.
Add the cold sourdough discard and mix with the dough.
Gradually add the heavy cream until the dough holds together.
Roll out the dough and cut into biscuits.
Bake at 450 degrees F for 15 minutes.
Brush the tops with melted butter before serving.