In a large bowl, mix together the flour, sugar, baking powder, baking soda and salt. In a separate bowl, whisk together the buttermilk and melted butter.
Sprinkle the cinnamon over the mixture. Stir until combined.
Cover and refrigerate overnight.
The next morning, preheat oven to 375 degrees F (190 degrees C). Grease a 9x13 inch pan.
Roll out dough onto a lightly floured surface. Cut into 12 equal pieces and place in the prepared pan.
Bake for 15 to 20 minutes in preheated oven. Serve warm.