Add the cold butter, then mix (preferably with a paddle attachment) until you have a cornmeal texture.
Add ¾ cup of the milk, vanilla and orange zest and mix until completely combined (to zest an orange, use a zester, paring knife or vegetable peeler to remove only the colored part of the skin).
Roll out the dough (if desired, roll it out a second time) and cut into circles.
Place on a baking sheet, brush the tops with remaining milk, and sprinkle with sugar.
Bake for 10–15 minutes, until golden brown.
Assembly
Slice the biscuits in half and place on plates.
Spoon some of the berry mixture on the bottom half and top with a dollop of fat-free whipped cream.
Cover with the top half of the biscuit and add some more berries and whipped cream.