What prompt format/template should I use for training Unsloth/Phi-3.5-mini-instruct?

Hi, I need some help figuring out the best way to format my prompts for my dataset based on the model I’m training, and I’d appreciate some advice. Should I keep it as it is, or use a chat template? Which approach should I use, and how should I format my prompts? I’m planning to run the model using an API I’ll code. Below I have attached my current format prompt that I am using to train my Unsloth/Phi-3.5-mini-instruct Model.

Example of my current format prompt
```
from datasets import Dataset

def format_prompt(example):
    return f"### Input: {json.dumps(example['input'], ensure_ascii=False)}\n### Output: {json.dumps(example['output'], ensure_ascii=False)}<|endoftext|>"

formatted_data = [format_prompt(item) for item in file]
dataset = Dataset.from_dict({"text": formatted_data})
```
Example of my dataset input and output
```
{
    "input": {
      "insight_period": "7-Days",
      "receipts": [
        {
          "merchantName": "Lane7",
          "date": "2026-06-08",
          "total": 21.02,
          "currency": "£"
        },
        {
          "merchantName": "LVLS",
          "date": "2026-06-07",
          "total": 53.78,
          "currency": "£"
        }
      ]
    },
    "output": {
      "insights": [
        {
          "title": "Balanced Spending",
          "description": "You spent £74.80, which falls within a reasonable range. The majority of your spending came from Entertainment. There is a consistent pattern in your recent transactions."
        },
        {
          "title": "Spending Pattern",
          "description": "You made 2 transactions during this period."
        },
        {
          "title": "Category Insight",
          "description": "Your highest spending category was Entertainment."
        }
      ],
      "category": "Entertainment"
    }
  }
```