minecraft-assets/data/minecraft/recipes/purpur_block.json

{
  "type": "minecraft:crafting_shaped",
  "pattern": [
    "FF",
    "FF"
  ],
  "key": {
    "F": {
      "item": "minecraft:popped_chorus_fruit"
    }
  },
  "result": {
    "item": "minecraft:purpur_block",
    "count": 4
  }
}