Separate the ramp bulbs and stems from the leaves. Roughly chop the bulbs and stems. Set aside 12-15 of the best ramp leaves for the crispy garnish and roughly chop the remaining leaves.

Pat the reserved ramp leaves completely dry with paper towels. Heat 120ml olive oil in a small saucepan over medium-high heat until it reaches 180°C. Fry the leaves in batches for 15-20 seconds until crispy but still green. Transfer to a paper towel-lined plate and sprinkle with flaky sea salt.

In a large Dutch oven or soup pot, melt the butter with 1 tablespoon olive oil over medium heat. Add the chopped ramp bulbs and stems along with the sliced leek. Sauté for 5-6 minutes until softened and fragrant.

Add the minced garlic and cook for 1 minute until fragrant. Add the cubed potatoes, vegetable stock, thyme, bay leaf, salt, and white pepper. Bring to a boil, then reduce heat and simmer for 20-25 minutes until potatoes are completely tender.

Remove the bay leaf. Add the chopped ramp leaves and cook for 2 minutes until wilted. Remove from heat and let cool slightly for 5 minutes.

Using an immersion blender, purée the soup until completely smooth. Alternatively, blend in batches in a standing blender, being careful with hot liquid.

Return the soup to low heat and stir in the heavy cream. Heat gently for 3-4 minutes until warmed through. Adjust seasoning with additional salt and pepper to taste.

Ladle the soup into warmed bowls. Add a small dollop of sour cream to each serving and top with several crispy ramp leaves. Serve immediately while the garnish is still crispy.