Thaw raspberries and crush them thoroughly (I use a potato masher for this). Measure exactly 2 cups of the crushed berries into a large bowl. Stir in sugar until thoroughly combined. Scrape sides of the bowl to incorporate sugar crystals along the edges. Cover bowl with plastic wrap or a plate and let stand at room temperature for 6-8 hours.
See Café Tips above for more detailed instructions and further tips.
Adapted from Kraft.