Check your goal menu to make sure you do have this goal offered--I'm not sure what level it's available at. Assuming you do have the goal, then you have to first do the step where you buy wallpaper & tiles yet. You don't have to buy the specific ones the goal says to buy, but you do have to purchase 8 & 12, respectively, of them to move on to the ovens.
(Also, you can store one or more of the appliances you have out in order to place/build more beehive ovens)
Here's the goal thread so you'll know what you're up against and can ask more goal-related questions if you have them:
https://forums.storm8.com/showthread...y-21-(15-Days)
Just FYI, it's not technically a side goal, it's one of the beginning goals that teach you how to play the game. Which is good, because that means it's untimed so you can go as slowly as you need to!
Anyway, yes, cupcake trees will unlock as you progress, but you have to do the other goal in your goal clipboard: build SweetCo stations and buy waterfalls. SweetCo station is also where the Fluffalanches are.
Here's more info:
https://forums.storm8.com/showthread.php?49249