Purée raspberries, sugar, lemon juice, lemon zest and Simply Lemonade® with Raspberry in a food processor or blender until smooth. Strain purée through a fine-mesh sieve into a 13x9x2 inch baking pan, pressing on solids.

Freeze mixture until edges begin to set, about 30 minutes. Using a fork, scrape to break up frozen portions around the edges. Freeze, scraping and breaking up mixture every 20–30 minutes, until mixture resembles fluffy shaved ice, 2–4 hours.