minecraft-assets/data/minecraft/recipe/polished_deepslate.json

{
  "type": "minecraft:crafting_shaped",
  "category": "building",
  "key": {
    "S": {
      "item": "minecraft:cobbled_deepslate"
    }
  },
  "pattern": [
    "SS",
    "SS"
  ],
  "result": {
    "count": 4,
    "id": "minecraft:polished_deepslate"
  }
}