My recipe calls for 2 cups shortening (Mom used all butter) ,cooks in a bundt pan. I was thinking of changing it to 1/2 c. cashew butter , 1/4 c. butter, 1/4 c. coconut oil. Would this be equivalent?
This is quite a bit of experimentation! First off, your measurements should be equivalent -- so if your recipe calls for 2 cups of fat, make sure you're swapping it out for 2 cups of a different kind of fat. I would nix the cashew butter (it won't behave similarly at all), but a combination of butter and coconut oil should work just fine (and actually lend a nice flavor to the finished product).
Before answering this, I'd want to see the entire recipe. What kind of a pudding is it? What are the other ingredients and their quantities? How is the carrot prepared before adding? There are so many factors to consider . . . ;o)
If this is a steamed pudding, my experience may help. I couldn't bear to put in all the butter in my old plum pudding recipe so I've gradually cut it down to half, & found I can even use margarine while still getting a good result.