Place the mango, coconut milk, and lemon juice in a high-speed blender. Blend until smooth.

Pour the mixture into a 9 by 13-inch glass baking dish. You can use a 9x9 if you can't fit a 9x13 in your freezer, the bigger the pan/more surface area the better though. Place the dish into the freezer to chill. Every 30 minutes, scrape the mixture with a fork to break up the ice crystals and to keep it light and fluffy. Continue scraping every 30 minutes for at least 3 hours. After that you can just keep it in the freezer until you're ready to eat.

Serve topped with coconut milk whipped cream and mango slices if desired. Enjoy!