Emily's Pumpkin Bars

• 18 1/2 box cake mix (yellow)
• 3 eggs divided use
• 1/2 stick
• 500 gr pumpkin divided use
• 250 gr sugar divided use
• 170 gr butter
• 160 ml evaprorated milk
• 60 gr walnuts (chopped optional)
• 3 gr cinnamon
• 2 gr ginger