minecraft-assets/assets/minecraft/recipes/gold_ingot_from_nuggets.json

{
  "type": "crafting_shaped",
  "group": "gold_ingot",
  "pattern": [
    "###",
    "###",
    "###"
  ],
  "key": {
    "#": {
      "item": "minecraft:gold_nugget"
    }
  },
  "result": {
    "item": "minecraft:gold_ingot"
  }
}