Can the sugar in the recipe be reduced?

I frequently reduce sugar, sometimes considerably, in recipes for baked goods. They usually turn out just fine.

Here's a helpful resource I found on this, specifically dealing with brownies: https://healthyeating.sfgate.com/cut-down-sugar-brownies-3822.html.

Granted, most brownies have flour in them, which no doubt affects the outcome, but I would still start with a small reduction here. I'd reduce the sugar to one cup and use one whole egg + 1 yolk. In fact, I'm going to try it myself within the next month or two. ;o)

Agree with drbabs.
Also, with so few ingredients, altering the ratios among them may well harm the results.
Perhaps look for another existing and tested recipe for flourless brownies with no or low sugar...
I find those alternatives work better when I am cooking for special diets or allergies.

It’s so hard to answer this. It’s a brand new recipe, and it’s based on a tried and true recipe that works really well. So I suppose, in theory, that you could cut the sugar back a little (maybe to 1 cup?). But the author has tested it with this much sugar, and walnuts are inherently a little bitter, so I’d probably make it with the full amount of sugar if I were to make it (which I probably will, for my chocolate loving friend who has celiac).