Once the seeds have completely cooled, divide into two even batches. Pour the first batch into the bowl of a food processor and combine with 1 cup granulated sugar. Pulse for about 20 seconds until finely ground, and the seeds have evenly distributed throughout the sugar. The mixture should be light gray in color and resemble super-fine cornmeal in texture. Be careful not to overprocess, or you'll end up with sesame butter! 20 seconds should do the trick. Repeat with the remaining batch of sesame seeds and the other remaining 1 cup granulated sugar. Combine the two batches of sesame sugar into the same airtight container and store in the refrigerator until ready to use. The mixture will keep for up to 1 month.