I don’t think it’s a long shot really – I bake with yogurt, fruit and veg purees, etc, and it’s not a sacrifice but often an enhancement.
The challenge for most American baked good recipes is the level of sweetness called for – if you cut that back by 50-75%, I don’t think you give up actual flavor, but it’s a decent drop in calories.
If yogurt or fruit / veg replaces part or all of the fat, that’s another calorie cut.
Then the biggest calorie count is the flour.
You just have to play with a bit to get it to what you are looking for.
Take this banana bread recipe which has become our house favorite – if the bananas are ripe / overripe, I have cut the actual number of bananas used by half, cut sugar from 1 cup to 1/4 cup, and swapped the egg and butter for yogurt (whole or 2%). You can forego the chocolate chips for cocoa or other flavorings.
Beyond that, what @ipsedixit said – I’d rather eat less of a real thing than more of something that’s clearly less-than. Cut a regular brownie recipe into smaller pieces and freeze. Make mini muffins instead of regular muffins. And so on. Satiety is a funny thing – your brain retrains itself.
