Sausage pea and potato pie – Hafners of Dublin

Ingredients

• 750g Maris Piper potatoes, peeled, chopped
• 25g butter
• 150ml milk
• Salt and pepper
• 100g Cheddar cheese, grated
• 1 packet of Hafner’s sausages
• 1 tablespoon olive oil
• 1 onion, finely chopped
• 200g bacon, roughly chopped
• 25g flour
• 250ml milk
• 1 teaspoon english mustard
• 150g frozen peas