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

{
  "type": "minecraft:crafting_shaped",
  "pattern": [
    "NN",
    "NN"
  ],
  "key": {
    "N": {
      "item": "minecraft:nether_brick"
    }
  },
  "result": {
    "item": "minecraft:nether_bricks"
  }
}