As much as I love the bold caramel flavor of deeply toasted sugar, I'll be the first to admit that it's a huge investment of time. Transforming a few pounds of granulated sugar from snow white to golden brown without melting it (!) can take up to six or seven hours in a low oven. It's not a lot of work, but it does take some babysitting, as the sugar needs to be stirred from time to time to encourage evaporation and promote even caramelization.
When I toast sugar at home, it's not always a daylong affair. Ninety-five percent of the time, I stop after about two or two and a half hours, when the sugar is a soft beige or manila-folder color. At that stage, it doesn't have a pronounced caramel flavor, but it tastes dramatically less sweet, with a richness uncharacteristic of plain sugar. It's sort of like the umami of sweetness, more satisfying in a way that's hard to describe unless you've tasted it for yourself.
Still, two hours is a solid chunk of time. You can passively toast sugar by using it as a pie weight in place of rice or beans when blind-baking a crust, but you can also toast even smaller quantities in just 30 minutes at 350°F (177°C).
The trick is to use a heavy 10- or 12-inch skillet, and limit the sugar to a quarter-inch-thick layer, so it toasts evenly without requiring any stirring.
As with toasting a batch of pecans, the exact timing will vary depending on the accuracy of your oven. If it runs hot, you'll have a hot mess in no time. If you don't have the assurance of a reliable oven thermometer, keep a close eye on the sugar your first time around, then adjust the temperature for future batches accordingly.
Toast the sugar until it has a strong caramel aroma, but exhibits a rather subtle color change. Under a dingy oven light, you may not even notice the color shifting at all, so grab a spoonful of plain sugar for comparison.
It's important to stop before the sugar looks damp, a change that signals liquefaction is imminent—when you're dealing with small quantities of sugar in a metal skillet inside a 350°F oven, there's only a brief window of time between dry and wet, which will make the sugar lumpy and hard. With larger quantities, lower temperatures, and less conductive materials, like glass or ceramic, that window opens up considerably, allowing for the deeper degrees of caramelization shown in my original post on this sugar caramelization method.
But, on those occasions when you suddenly want a cup or two of toasted sugar for an Angel Food Cake or Sugar Cookies, this technique offers the best ratio of effort to reward, turning plain white sugar into something less sweet and more flavorful in just 30 minutes.