Preheat the oven to 200°C/400°F/Gas mark 6
Cream together the butter, sugar and sour cream. Stir in the buttermilk and vanilla. Sift together the flour, soda and salt; stir in to the creamed. Chill the dough for ten minutes.
Drop by teaspoonfuls of dough 2" apart on lightly greased sheet. Mix together the cinnamon and sugar and sprinkle on the cookies. Bake in the preheated oven for 8-10 minutes. Cool a little in the oven, then remove to a wire rack to cool completely.
