You can do this the old fashioned way and add ingredients to a mason jar, cover with the lid and shake vigorously for 10 minutes, or you can use the food processor.
In a food processor bowl add all the ingredients and turn on high. The liquid will slosh, whip and then separate after about 4 minutes. When the mixture separates, (these are the butter solids and buttermilk), stop processing and strain out the buttermilk - there will be just under a cup. Reserve the buttermilk to make the scones. Strain out the butter and squeeze dry. Work the butter a couple of times to bring it together to form a nice ball. Refrigerate butter until ready to use.
For the scones: Preheat oven to 400°F.
In a food processor bowl add flour, sugar, baking powder, baking soda and salt. Add cold butter cubes and pulse until you have the texture of coarse bread crumbs. Transfer to a large mixing bowl, then add 3/4 cup of buttermilk and stir to combine. As it comes together add berries and fold dough to incorporate berries but not break them up too much.
Drop spoonfuls of dough onto a parchment lined sheet pan. Using a pastry brush, paint the tops of each scone lightly with buttermilk and sprinkle with sugar.
Bake until golden brown, and nice and puffy, about 17 to 20 minutes. Remove from the oven and transfer to a wire rack.