Yes, in baking you should definitely not substitute whipped cream for butter, that would go very poorly.

But there's rarely any advantage to fancy butter in baking either, unless you're making something like croissants where the butter is a main component of the final flavor.

Cream still has some whey in it, and whipping it just suspends it, where fully churning or overwhipping it separates it out so the remainder is purer fat

One interesting thing you can do in order to separate the whey from the fat in cream is (something very much like) freeze-distillation.

There is a cold spot in my refrigerator (not the freezer!) where the ambient temperature is approximately 25 °F. If I put a carton of heavy cream there, in several days the contents will have largely separated—there will be a solid chunk of milkfat, and some liquid whey.

Having drained the whey, I can then beat the milkfat with an electric mixer. This causes the remainder of the whey to separate out (due to centrifugal force); after draining this remnant whey, I am left with butter.

The advice in this post is based on very flawed assumptions, but if you’re inclined to take it anyway (or to do something else in this vein), then note that there’s an easier way than using such a complex contraption as an eggbeater.

You will need the following:

1. 2-cup-capacity Pyrex measuring cup (image).

2. Large wire whisk (image).

Pour no more than 3/4 cup cream into Pyrex measuring cup. Hold whisk vertically, with its business end fully immersed in the cream, and with the handle between the palms of your hands. Move your hands back and forth vigorously, so as to roll the whisk between your palms.

This will whip the cream, in relatively short order (though not as quickly as if you used an electric hand mixer).

Generally, I'm not very sure why you would use whipped cream instead of butter.

This post is based on my (apparently not universal!) understanding that whipped cream is far tastier than butter.

You can keep butter in your fridge for weeks and it will stay fresh enough to use. (If you’re fussy you can scrape off a thin layer of slightly-oxidized butter from the surface.) You can’t do that with cream.

Yes, you absolutely can do this with cream. Cream doesn’t go bad for quite some time—it can easily keep for 2 or 3 weeks, even longer. (In fact, I have never seen cream go bad—though I haven’t deliberately tested it, the point is that your cream accidentally going bad is very unlikely.)

This is probably another preference thing, but I'm quite happy to eat plain whipped cream on plain berries (or Key lime pie, or cobbler). They're all plenty sweet as is.