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

{
  "type": "minecraft:crafting_shaped",
  "category": "building",
  "key": {
    "#": "minecraft:nether_brick_slab"
  },
  "pattern": [
    "#",
    "#"
  ],
  "result": {
    "count": 1,
    "id": "minecraft:chiseled_nether_bricks"
  }
}