Sift flour, sugar, salt and baking powder together into a large bowl. Using a pastry blender or two knives, cut the butter into the dry ingredients until mixture resembles peas. Pour in the cream and stir in with a fork until the dough comes together. Repeat process until most of the dough is used.
Transfer rounds to a greased baking sheet.
Sprinkle tops with extra sugar and bake for 10 minutes, or until golden brown. Assemble dessert by slicing biscuits in half and topping with mixed berries. Replace top half and top with more berries.