Reduce Sweetness in Fudge
Traditional &quot;fudge&quot; gets its structure primarily from the sugar, which forms fine crystals; the texture of fudge is a stiff suspension of the sugar in the fat. So simply reducing the proportion of sugar will mess up the texture, as GdD alluded to.
But fudge isn't the only thickened-fat confection out there! One dish that immediately comes to my mind is sesame halwa, which uses the sesame particles in the same way fudge uses the sugar particles. Nut butters generally have a similar suspension (if you've had &quot;natural&quot; peanut butter without hydrogenated oils, or tahini or sesame sauce for that matter, think of the extra-thick layer that forms when it hasn't been stirred).
So I think you could temper the sweetness by combining a fudge recipe with something like sesame halwa, or by adding peanut flour as a substitute for some of the sugar. If you use light-colored peanut flour I don't think it would even affect the taste too much (other than reducing the sweetness, of course).