I LOVE cake batter and using it for pies is awesome. I get many questions about using cake batter pies so here is my go too. I generally start with 2 cups water per 4 mixes then go from there adding more water as needed. IF you get white cake mix and warm up frosting and add it in your mix will be thicker and more sticky. Mix and match colored cake batter too create colorful pies. It is also my GO too for making slime , simply leaving it a bit thinner and add frosting or food coloring for slime. White cake mix is cheap, readily available, and is awesome. In my experience I have filled 14 standard pie tins with cake batter using 3 one gallon buckets worth of cake batter mixing the colors.
Not so far I did have a white T shirt that I thought was stained but that was with chocolate syrup and I got that clean so . Any undies I have filled came out clean so. I can't recommend you wear white though and if you do it might take a couple of washes to come out, make sure your using good detergent and washing them right away I think mine was stained cause I let it dry before throwing it in the wash so.
Love you, too
