I'm making a last minute cake for a friend. Her daughter was just diagnosed with celiac disease today. Her first birthday party is scheduled for Saturday. I have celiac disease myself so she came to me asking if I could help her out with a smash cake. I can make a gluten free cake no problem, but her daughter is also allergic to dairy and soy. Can I substitute canola oil for butter in my vanilla cake recipe? If not could I substitute Spectrum shortening for butter?

Does spectrum shortening work fine for buttercream? I assume it does, but I haven't tried it before so I want to ask to make sure.

I have celiac also, that said, shortening would be fine for a buttercream type icing, I'm not familiar with spectrum brand thus can't say, I have used both canola oil and a very light olive oil (no discernible taste and the gf cakes have come out fine)

Our dairy-free/soy-free frosting uses Spectrum palm oil shortening, and we use ground flaxseed as a substitute along with our gluten-free flour mix (rice flour, sorghum flour, tapioca starch, and xanthan gum) for gluten/dairy/soy-free cake.

Thanks everyone. I ended up using canola oil for the butter and rice milk for the milk and used my regular gluten free vanilla cake recipe. It was fine, though I'm not sold on the oil, I might try something different next time. The Spectrum shortening worked just fine for the buttercream. The mom was very happy to have a cake for her baby. She was worried she wouldn't be able to get her a cake for her first birthday.

Glad to hear it turned out well, hopefully with the significant increase in allergic reactions, et. al. , companies will continue to invest R & D in new healthy, good tasting products.