Shephards Pie - Ziggys

Ingredients

• 500g pork mince
• 1 tablespoon oil
• 1 onion, finely chopped
• 1 stick celery, sliced thinly
• 1 carrot, peeled and diced
• 3 tablespoons tomato sauce
• 2 tablespoons Worcestershire sauce
• 2 tablespoons gravy powder
• Pinch of white pepper
• 3/4 cup chicken stock
• 1kg mashed potatoes
• 40g butter
• ½ cup tasty cheese, grated