01 - 
                        2 tbsp vegetable oil, for caramelizing onions.
                      
                    
                      
                        02 - 
                        1 large onion, thinly sliced, for a sweet and savory base.
                      
                    
                      
                        03 - 
                        4 oz baby bella mushrooms, sliced, for earthiness.
                      
                    
                      
                        04 - 
                        2 tbsp unsalted butter, for cooking apples.
                      
                    
                      
                        05 - 
                        1 ½ Granny Smith apples, cubed, for a tart and sweet contrast.
                      
                    
                      
                        06 - 
                        1 tsp granulated sugar, to enhance apple sweetness.
                      
                    
                      
                        07 - 
                        1 ½ oz grated Gruyère cheese, for creamy richness.
                      
                    
                      
                        08 - 
                        2 tbsp minced chives, for freshness.
                      
                    
                      
                        09 - 
                        ½ tsp dried thyme, for a hint of herbaceousness.
                      
                    
                      
                        10 - 
                        1 lb puff pastry, thawed, for the flaky base.
                      
                    
                      
                        11 - 
                        1 egg, beaten, for brushing the pastry.