Looking at the Banana Refrigerator Cake (RHC) vs. the Cordon Rose Banana Cake (TCB), the only material difference, if my memory is correct, is that the BRC uses oil and the CRBC uses butter (same weight). This leads me to believe that you can, generally, sub oil for butter if you choose—of course, oil cakes are moister and have what is to me a ‘spongy’ texture, but many people love them. However, and I may be mistaken here, I think an oil cake vs. a butter cake has more fat (because oil is 100% fat where butter is 80% fat and 20% water), but obviously, less saturated fat.
Of course, there are many things at work when looking at the healthiness or unhealthiness of a dessert—for example, refined vs. whole grains (and of course we’re using super-refined with cake flour and bleached AP flour), and the fact that fats and protein slow the uptake of sugar and the glycemic ‘hit’ of foods—and the harder that ‘hit’, the more insulin is triggered, which leads to fat production in the body and insulin resistance, generally if this is a frequent occurrence—so fat, in a way, is helpful to desserts. Also, butter is somewhat less refined than oils, and the refining process can have many adverse health risks, so there’s that balance. And that’s only the tip of the iceberg. The final word is that health guidelines have changed and changed and changed, so what we ‘know’ today may be tomorrow’s ‘old misguided science.’ Take eggs and coconut—and even saturated fat is starting to becoming ‘unvillified,’ so we’ll see where that leads!
Thus, my suggestion is if you are concerned about limiting health risks, make baby cupcakes to reduce the serving size!!
One thing you can do is make a small batch with your proposed modifications and see if its taste and texture is what you want it to be—if not, experiment further until it is!! It’s fun to experiment, and I hope you are able to achieve your desired results.
I know one person on our forum subs coconut oil for butter for its health benefits—you get a bit of coconut flavor, which can be nice, so that’s another thought. Someone else will likely chime in with more ideas!
Good luck, and I look forward to hearing the results and seeing your cuppies!!!!!