To make ice cream in the game Grow a Garden, you need to combine specific plant ingredients at the Cooking Pot on the island. The basic process is to equip the ingredients you want to add, interact with the pot to add them, then cook the mixture to get ice cream. Different ingredient combinations result in ice cream of varying rarity levels:

• Uncommon Ice Cream: Corn + Blueberry or Corn + Strawberry
• Rare Ice Cream: Watermelon + Corn or Blueberry + Banana
• Legendary Ice Cream: Banana + Watermelon or Banana + Apple or Mango + Corn
• Mythical Ice Cream: Banana + Pepper or Banana + Loquat or Corn + Sugar Apple
• Divine Ice Cream: Sugar Apple + Sugarglaze

After adding the ingredients to the Cooking Pot and confirming the recipe, press Cook to prepare the ice cream. You can take ingredients out before cooking if needed. After cooking, interact again to collect your ice cream, which can be given to Chris P. Bacon for rewards. In summary, making ice cream in Grow a Garden involves growing or gathering the right plant ingredients, adding them to the Cooking Pot, cooking, and then collecting the finished ice cream. The combinations of plants determine the rarity and type of ice cream you produce.