Melt the butter in a large saucepan over a medium heat and sweat the onion for 5-6 minutes until it starts to soften. Add the garlic and most of the peas (reserve a large handful), stir well and cook for 1-2 minutes stirring occasionally.
Cover with the stock, bring to the boil, then reduce to a simmer for 10-15 minutes. Transfer to a food processor and blitz until smooth. Return to the saucepan and add the reserved peas, heating over a gentle heat.
Meanwhile, heat the grill to hot and grill the bacon until golden and crispy; 3-4 minutes on both sides. Adjust the seasoning of the soup, then remove the bacon when it's ready and chop. Finish the soup by stirring in the mint, then ladle into soup bowls.
Sprinkle the chopped bacon on top and drizzle each soup with a little olive oil. Serve immediately.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.