VanillaPlus/temp/vertrecipes/vertical_polished_blackstone_brick_slab.json

{
    "type": "minecraft:crafting_shapeless",
    "ingredients": [
        {
            "item": "minecraft:polished_blackstone_brick_slab"
        }
    ],
    "result": {
        "item": "vplus:vertical_polished_blackstone_brick_slab"
    }
}