Can I use Brown Sugar instead of Granulated Sugar in my No Bake Cookie Recipe?
In many recipes, brown sugar and granulated sugar can be substituted for each other fairly freely. Keep in mind that brown sugar will add both color and flavor, and it has more moisture. If your recipe has a narrow moisture tolerance, you'll want to decrease the moisture elsewhere. Also, brown sugar tends to be more hygroscopic than granulated, so the product will remain softer over time.
Today "Brown Sugar" is a mixture of granulated sugar and molasses. As a substitute for granulated sugar brown sugar is "OK" but it will be significantly more sweet than just sugar, unless you dial back the quantity of sugar, which may be problematic for the overall recipe. Some experimentation may be required for your recipe(s) but it will get you close.