→ For the Streusel
                    
                      
                        01 - 
                        3 tablespoons granulated sugar
                      
                    
                      
                        02 - 
                        ¼ cup brown sugar
                      
                    
                      
                        03 - 
                        1¼ teaspoons cinnamon
                      
                    
                      
                        04 - 
                        ½ teaspoon ground ginger
                      
                    
                      
                        05 - 
                        pinch salt
                      
                    
                      
                        06 - 
                        6 tablespoons unsalted butter, melted
                      
                    
                      
                        07 - 
                        1¼ cups all-purpose flour
                      
                    
                      
                        08 - 
                        ⅓ cup semi-sweet chocolate chips
                      
                    
                      
                        09 - 
                        ⅓ cup chopped walnuts (optional)
                      
                    
                  
                    → For the Cake
                    
                      
                        10 - 
                        2½ cups all-purpose flour
                      
                    
                      
                        11 - 
                        2 teaspoons baking powder
                      
                    
                      
                        12 - 
                        ½ teaspoon baking soda
                      
                    
                      
                        13 - 
                        ½ teaspoon salt
                      
                    
                      
                        14 - 
                        1¼ cups granulated sugar
                      
                    
                      
                        15 - 
                        ¼ cup brown sugar
                      
                    
                      
                        16 - 
                        ¾ cup unsalted butter, room temperature
                      
                    
                      
                        17 - 
                        3 large eggs, room temperature
                      
                    
                      
                        18 - 
                        2 teaspoons vanilla extract
                      
                    
                      
                        19 - 
                        1 teaspoon lemon juice
                      
                    
                      
                        20 - 
                        1¼ cups sour cream
                      
                    
                      
                        21 - 
                        1 cup semi-sweet chocolate chips
                      
                    
                      
                        22 - 
                        ½ cup chopped walnuts (optional)