I found this recipe by Pam Bell at Skinny Sweets Daily. The PinchIt button didn't work so I've had to retype it. I have never used seltzer in a cake before but may solve my hesitation with making a pumpkin dump cake, that being the heaviness of the pumpkin. Since this is October, as soon as the family finishes yesterday's bake, this will be up for trial.
Preheat oven to 350 degrees, mist a square cake pan with cooking spray and set aside.
In a large mixing bowl, add all ingredients except the chips and cinnamon sugar.
Using a hand held mixer, mix until all is combined and batter is fluffy. Use a rubber spatula to dip down deep to get any dry mix, make sure all is completely mixed well.
Pour batter into pan and smooth out. Toss chips if using and sprinkle cinnamon sugar over the top of cake.
Bake around 30 to 40 minutes until cake springs back when lightly touched and toothpick comes out clean or with dry to moist crumbs. Try not to over bake. Check after 30 minutes. Return to oven if needed.
Let cake cool in pan until almost completely cooled. Cut into squares and enjoy!