minecraft-server-resource-pack/packs/0-lzcustom/assets/minecraft/items/cake.json

{
  "parent": "minecraft:item/generated",
  "textures": {
    "layer0": "minecraft:item/cake"
  },
  "overrides": [
    {"predicate": {"custom_model_data":59700}, "model": "lz:food/plated_cake_slice"}
  ]
}