1
                    
                    Pre-heat the oven to convection bake at 450°F.
                 
                
                    2
                    
                        
                                    - 
                                        
                                            4½
                                                cups
                                         flour, all-purpose 
- 
                                        
                                            2
                                                tsp
                                         cream of tartar 
- 
                                        
                                            2
                                                tsp
                                         baking soda 
- 
                                        
                                            1½
                                                tsp
                                         salt 
 
                    Combine the flour, cream of tartar, baking soda, and salt in a large mixing bowl.
                 
                
                    3
                    
                        
                                    - 
                                        
                                            ½
                                                cup
                                         butter (frozen, diced) 
 
                    Cut the cold butter in the dry ingredients with a pastry blender until the mixture resembles pea-sized crumbs. Refrigerate for 20 min if the butter gets soft during this process.
                 
                
                    4
                    
                        
                                    - 
                                        
                                            9
                                                tbsp
                                         butter (softened) 
- 
                                        
                                            3
                                                tbsp
                                         butter (melted) 
- 
                                        
                                            2
                                                cups
                                         buttermilk 
 
                    Cut the cold butter in the dry ingredients with a pastry blender until the mixture resembles pea-sized crumbs. Refrigerate for 20 min if the butter gets soft during this process.
                 
                
                    5
                    
                    Add 1½ cups of buttermilk, stirring enough to moisten the ingredients (adding more 1 tbsp at a time, if needed).
                 
                
                    6
                    
                        
                                    - 
                                        
                                            9
                                                tbsp
                                         butter (softened) 
- 
                                        
                                            3
                                                tbsp
                                         butter (melted) 
 
                    Being careful not to overwork the dough, kneed the dough 10 times on a lightly floured surface or until the dough just holds together. Roll or pat out into a 14×10" rectangle.  With the short side nearest you, spread 3 tbsp of the softened butter over the ⅔ of the surface farthest from you.  Fold the dough in thirds (like a letter) by pulling the bottom over the center and then the top third over that. Expect the dough to crack during this process. Pat back into a 9×12" rectangle and repeat the same process twice more with another 3 tbsp of the softened butter each time. Finally, pat the dough out into a 1" thick rectangle.  Cut the dough into 2-3" squares using a scraper and place on a lightly oiled cooking sheet about 1" apart. Brush the tops with the melted butter.
                 
                
                    7
                    
                    Place in the oven and bake until the tops are golden brown and firm (about 8–12 minutes).