Preheat the oven to 350 degrees and grab a 9x13 greased baking dish. You'll want to think of these bars as 3 layers.
To make the first layer, divide the yellow cake mix and place all but one cup in a mixing bowl. Stir the melted butter and one egg into the cake mix.
This will create a creamy yellow consistency. Take this and spread it evenly into the baking dish. I used my hands to push it in there to get it nice and even.
Next, mix the jar of pumpkin butter with two eggs and milk. Pour this over the first layer.
Finally, make the top layer. Stir the reserved cup of cake mix with the flour, sugar, softened butter, and cinnamon. Make sure the butter is soft so it all combines well. Keep on mixing until it becomes crumbly.
Sprinkle this over the pumpkin layer right on top. Pop it into the oven and bake for 35-40 minutes until the top is golden brown.Let the pumpkin bars cool and cut into 2" squares.