Preparing as much as possible of a cake in advance It's my girlfriend's birthday this WE and I plan on secretly preparing a cake she likes. However, we'll be in the countryside with friends this WE, and I'll have very limited time to prepare on site without getting caught.

So my plan it to prepare/mix as much as possible before hand, and do as little as possible there before throwing the whole thing in the oven. 

However, I have little experience in deserts, and I need help determining what can/can't be done the day before.

Here's the recipe: https://www.noracooks.com/vegan-chocolate-cake/

Two parts:


The (chocolate) cake itself


1 cup unsweetened almond milk
1 tablespoon apple cider vinegar
2 cups all purpose flour
1 3/4 cups granulated sugar
3/4 cup cocoa powder
2 teaspoons baking powder
1 1/2 teaspoons baking soda
1 teaspoon salt
1/2 cup canola oil OR melted coconut oil
2/3 cup unsweetened applesauce
1 tablespoon pure vanilla extract
1 cup boiling water

Chocolate Buttercream Frosting


1 cup cocoa powder
1 1/2 cups earth balance vegan butter, softened baking sticks preferred
4-5 cups powdered sugar
2 teaspoons pure vanilla extract
1/4-1/2 cup unsweetened almond milk



Can I safely prepare the chocolate cake batter on one side, and the buttercream frosting on the other side, the day before? I would keep them in containers, in the fridge...

Thanks!
If you look at how boxed cake mixes do it, you'll get the right idea. They combine the dry ingredients and you have to add the wet ingredients. There are a couple of good reasons for this: spoilage (not too much of a problem if you're taking about a couple of days in the fridge); and gluten formation, which requires water and will give a tough, bready texture.

I suggest you mix the dry ingredients, and measure each of the wet ingredients into its own container (combining the apple sauce, vinegar and vanilla should be fine). Use containers that you can get everything out of or your measurements will be off. Then you don't need to refrigerate the oil or dry mix but do need to chill the wet mix and presumably the almond milk.

The buttercream should be fine made in advance - it certainly would be if it was based on dairy butter and milk. Of course this needs chilling. It also needs to be applied to a cool cake so it doesn't melt.

The other option is to bake the cake in advance and only ice it when you get there, but some recipes keep better than others. This has the advantage that the cake will definitely have cooled. I'm no expert on the keeping properties of vegan cakes in general, let alone this recipe, but many of the vegan cakes I've eaten have been the sort of thing that would keep their texture for a few days.