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

{
  "type": "minecraft:crafting_shapeless",
  "category": "building",
  "group": "planks",
  "ingredients": [
    "#minecraft:dark_oak_logs"
  ],
  "result": {
    "count": 4,
    "id": "minecraft:dark_oak_planks"
  }
}