1
                    
                    Preheat the oven to 400°F.
                 
                
                    2
                    
                    Peel and slice the sweet potatoes into ¼” slices. Arrange in a 9”⨉13” backing dish so that each slice overlaps slightly with the prior one, alternating colors to create a pleasing pattern.  Sprinkle with cheese, and then create a second layer of potato.
                 
                
                    3
                    
                        
                                    - 
                                        
                                            2½
                                                cups
                                         heavy cream 
- 
                                        
                                            1
                                                tsp
                                         thyme, dried 
- 
                                        
                                            1½
                                                tsp
                                         salt 
- 
                                        
                                            1½
                                                tsp
                                         pepper, black 
- 
                                        
                                            1
                                                tsp
                                         mustard powder 
- 
                                        
                                            ½
                                                tsp
                                         nutmeg, ground 
- 
                                        
                                            ¼
                                                tsp
                                         garlic powder 
- 
                                        
                                            ¼
                                                tsp
                                         onion powder 
 
                    Combine the cream and spices in a small saucepan.  Cook over medium-high heat until bubble just start to form.
                 
                
                    4
                    
                    Pour the cream mixture over the sweet potatoes in the baking dish. Sprinkle with the remaining cheese. Cover loosely with foil, and bake until the potatoes can be pierced effortlessly with a knife (about 45 minutes).
                 
                
                    5
                    
                    Remove the foil, and switch the oven to broil on its highest setting. Carefully Watch until the top layer has just started to brown, and then remove from the oven (about 1 minute).  Allow to cool for 10 minutes before serving.