renewable-resources/data/renewable/recipe/tuff.json

{
  "type": "minecraft:crafting_shaped",
  "category": "building",
  "pattern": [
    "GC",
    "CG"
  ],
  "key": {
    "G": "minecraft:gravel",
    "C": "minecraft:cobblestone"
  },
  "result": {
    "id": "minecraft:tuff",
    "count": 4
  }
}